REMIND(1)

NAME
remind - a sophisticated reminder service

THE BOOK OF REMIND
This man page is a good reference for Remind. However, if you are a novice wishing to learn Remind, I suggest downloading "The Book of Remind" from the Remind home page at the following URL:

        https://dianne.skoll.ca/projects/remind/

SYNOPSIS
remind [options] filename [date] [*rep] [time]

DESCRIPTION
Remind reads the supplied filename and executes the commands found in it. The commands are used to issue reminders and alarms. Each reminder or alarm can consist of a message sent to standard output, or a program to be executed.

If filename is specified as a single dash '-', then Remind takes its input from standard input. In this case, if Remind has been compiled against the GNU Readline library, it will use Readline to give you an interactive line-editing interface.

If filename happens to be a directory rather than a plain file, then Remind reads all of the files (but not any subdirectories!) in that directory that match the pattern "*.rem". The files are read in sorted order; the sort order may depend on your locale, but should match the sort order used by the shell to expand "*.rem".

Remind reads its files starting from the beginning to the end, or until it encounters a line whose sole content is "__EOF__" (without the quotes.) Anything after the __EOF__ marker is completely ignored.

MODES OF OPERATION
Remind has four major modes of operation:

Agenda Mode
    Agenda mode is the default mode. In this mode, Remind prints today's reminders on standard output and exits. It may fork a background process to pop up queued reminders for later in the day.

Calendar Mode
    In this mode, Remind generates a calendar either by drawing it in the terminal or by sending data in computer-readable format to a back-end program that actually draws the calendar.

Daemon Mode
    This is a special mode of operation in which Remind is invoked by a front-end and runs as a daemon, accepting requests from the front-end and sending messages back to the front-end. TkRemind uses Remind in daemon mode.

Purge Mode
    In this mode, Remind produces no output, but creates new versions of its input files with all expired reminders commented out.

OPTIONS
Remind has a slew of options. If you're new to the program, ignore them for now and skip to the section "REMINDER FILES".

-n  The -n option causes Remind to print the next occurrence of each reminder in a simple calendar format. You can sort this by date by piping the output through sort(1). Note that the -n option causes any -g option to be ignored and also implicitly enables the -o option.

-j[n]
    Runs Remind in "purge" mode to get rid of expired reminders. See the section PURGE MODE for details.

-r  The -r option disables RUN directives and the shell() function.

-c[flags]n
    The -c option causes Remind to produce a calendar that is sent to standard output. If you supply a number n, then a calendar will be generated for n months, starting with the current month. By default, a calendar for only the current month is produced. This option implicitly enables the -o option.

    You can precede n (if any) with a set of flags. The flags are as follows:

    '+' causes a calendar for n weeks to be produced.

    'a' causes Remind to display reminders on the calendar on the day they actually occur as well as on any preceding days specified by the reminder's delta. This also causes Remind to include text outside %"...%" sequences that would otherwise be removed (though the actual %" markers themselves are removed.)

    'l' causes Remind to use VT100 line-drawing characters to draw the calendar. The characters are hard-coded and will only work on terminals that emulate the VT00 line-drawing character set.

    'u' is similar to 'l', but causes Remind to use UNICODE line-drawing characters to draw the calendar. The characters are hard-coded and will only work on terminals that are set to UTF-8 character encoding. This flag also enables the use of the UNICODE "left-to-right" mark that can fix up formatting problems with right-to-left languages in the calendar display.

    'z' has the effect of setting the system variable $TerminalHyperlinks to 1. See the documentation of this variable in the section "SYSTEM VARIABLES"

    'c' causes Remind to use VT100 escape sequences to approximate SPECIAL COLOR reminders. Note that this flag is kept for backwards-compatibility; you should use the -@[n][,m][,b] command-line option instead.

    In a UTF-8 locale, Remind will use "left-to-right marks" when creating a calendar with the -c option. Some terminals don't handle this correctly and garble the rendering of the calendar; see the documentation of $SuppressLRM in the section "SYSTEM VARIABLES" for a workaround.

-@[n][,m][,b]
    Tells Remind to approximate SPECIAL COLOR and SHADE reminders using VT100 escape sequences. The approximation is (of necessity) very coarse, because the VT100 only has eight different color sequences, each with one of two brightnesses. A color component greater than 64 is considered "on", and if any of the three color components is greater than 128, the color is considered "bright".

    If you supply the optional numeric parameters, the have the following meanings: n=0 tells Remind to use the standard 16 VT100 colors. n=1 tells it to use an extended 256-color palette supported by many terminal emulators such as xterm. And n=2 tells it to use escape sequences that support true 24-bit colors, again supported by many terminal emulators such as xterm.

    If the optional m parameter is supplied following a comma, then m=0 tells Remind that the terminal background is dark, and Remind will brighten up dark colors to make them visible. If m=1, then Remind assumes the terminal background is light and it will darken bright colors to make them visible. If m is specified as 2, then Remind does not perform any adjustments, and some reminders may be hard or impossible to see if the color is too close to the terminal background color. If you supply the letter t rather than a number, then Remind attempts to guess the background color of the terminal, even if stdout is not a terminal.

    On startup, if the standard output is a terminal, Remind attempts to determine if the terminal background is dark or light by sending a special escape sequence to determine the background color. The m parameter can override this check (or force it if m is given as t.)

    If the optional b parameter is supplied following a comma, then b=0 tells Remind to ignore SPECIAL SHADE reminders (the default) and b=1 tells Remind to respect SPECIAL SHADE reminders by emitting VT100 escape codes to color the background of the calendar cell. Note that SHADE does not work well unless you are using the extended 256-color palette (n=1) or the true 24-bit colors (n=2). Note that for calendar cells that are shaded, the clamping mechanism described earlier for m=0 or m=1 is skipped; it is assumed that if you set both the foreground color of a reminder and the background color of a cell, then you know what you are doing.

-wcol[,pad[,spc[,spc2]]]]
    The -w option specifies the output width, padding and spacing of the formatted calendar output. Col specifies the number of columns in the output device. If col is not specified, or is specified as 0, it defaults to the larger of 71 or the actual width of your terminal, or to 80 if standard output is not a terminal. If col is specified as the letter t, then Remind attempts to get the width of the /dev/tty terminal device. This is useful, for example, if you pipe calendar output into less; even though standard output is a pipe, you want the calendar to be sized correctly for your terminal window:

            remind -c -wt .reminders | less

    Note that the value of col is also used to set the system variable $FormWidth, which is initialized to col - 8. See "SYSTEM VARIABLES" for details.

    Pad specifies how many lines to use to "pad" empty calendar boxes. This defaults to 5. If you have many reminders on certain days that make your calendar too large to fit on a page, you can try reducing pad to make the empty boxes smaller. Spc specifies how many blank lines to leave between the day number and the first reminder entry. It defaults to 1. spc2 may be 0 or 1 and it specifies whether or not blank lines should be printed in between reminders on the same day. The default is 1, which causes the blank lines to be printed.

    Any of col, pad or spc can be omitted, providing you provide the correct number of commas. Don't use any spaces in the option.

-s[a]n
    The -s option is very similar to the -c option, except that the output calendar is not formatted. It is listed in a "simple format" that can be used as input for more sophisticated calendar-drawing programs. If n starts with "+", then it is interpreted as a number of weeks. This option also implicitly enables the -o option. If you immediately follow the s with the letter a, then Remind displays reminders on the calendar on the day they actually occur as well as on any preceding days specified by the reminder's delta.

-p[a][p][p][q][+]n
    The -p option is very similar to the -s option, except that the output contains additional information for use by a back-end such as the Rem2PS program, which creates a PostScript calendar, and various other back-end programs. If n starts with "+", then it specifies a number of weeks rather than a number of months, and back-ends are expected to produce weekly calendars. Note that not all back-ends support weekly calendars; currently, only rem2pdf and rem2html do. Specifying a weekly calendar implicitly enables the pure JSON interchange format, similar to -ppp.

    The format of the -p output is described in the rem2ps(1) man page. If you immediately follow the p with the letter a, then Remind displays reminders on the calendar on the day they actually occur as well as on any preceding days specified by the reminder's delta. If you follow the p with another p, then Remind uses a more comprehensive JSON-based format rather than the "simple calendar" format. This format is also documented in the rem2ps(1) man page. Finally, if you use three p's, as in -ppp, then Remind uses a pure JSON format, again documented in rem2ps(1). If you include a q letter with this option, then the usual calendar-mode substitution filter is disabled and the %"...%" sequences are preserved in the output.

    Note that to pass INFO strings to a back-end, you must use -pp or -ppp. The simpler -p format is not capable of transmitting the INFO strings to the back-end.

    The -p, -pp and -ppp options implicitly enable the -o option.

    Note that the -pp or -ppp options also enable the -l option.

-l  If you use the -l option in conjunction with the -p option, then Remind outputs additional information for back-end programs such as rem2ps. This additional information lets the back-end programs correlate a reminder with the source file and line number that produced it.

-m  The -m option causes the -c or -p options to produce a calendar whose first column is Monday rather than Sunday. (This conforms to the international standard.)

-v  The -v option makes the output of Remind slightly more verbose. Currently, this causes Remind to echo a bad line in case of an error, and to print a security message if a script tests the $RunOff system variable.

-o  The -o option causes Remind to ignore all ONCE directives. Note that ONCE is also ignored if any of the -c, -n, -p, or -s options is used, if a repetition factor *n is used, or if a date other than today's date is specified on the command-line.

-t  The -t option causes Remind to trigger all non-expired reminders, regardless of the delta supplied for each reminder.

-tn If you supply a number n after the -t option, then Remind pretends that every REM command has a delta of ++n, regardless of any existing delta.

-tz If you supply the letter z after the -t option, then Remind sets all REM statements' deltas to zero, regardless of the value supplied in the REM statement itself. In effect, this disables all deltas of the form +n and ++n.

-tt[n]
    The -tt option causes Remind to assume a default delta of n minutes for all timed reminders. If -tt is given with no n, a default delta of 5 minutes is used.

-h  The -h option ("hush...") suppresses certain warning and information messages. In particular, if no reminders are triggered, this mode produces no output.

-a  The -a option causes Remind not to immediately trigger timed reminders that trigger on the current day. It also causes Remind not to place timed reminders in a calendar. If you supply two or more -a options, then Remind will trigger timed reminders that are in the future, but will not trigger timed reminders whose time has passed. (Regardless of how many -a options you supply, Remind will not include timed reminders in the calendar if at least one -a option is used.)

-q  The -q option causes Remind not to queue timed reminders for later execution.

-f  The -f option causes Remind to remain in the foreground when processing queued reminders, rather than forking off a background process to handle them.

-e  The -e option diverts error messages (normally sent to the standard error stream) to the standard output stream.

-dchars
    The -d option enables certain debugging modes. The chars specify which modes to enable:

    e   Echo all input lines

    x   Trace all expression evaluation

    t   Display all trigger date computation

    v   Dump the variable table after execution of the reminder script

    l   Echo lines when displaying error messages

    f   Trace the reading of reminder files

    p   Issue warnings if a POP-OMIT-CONTEXT, POP-VARS or POP-FUNCS matches a corresponding PUSH that is in a different file.

    s   Trace expression parsing and display the internal expression node tree. This is unlikely to be useful unless you are working on Remind's expression evaluation engine.

    h   Dump hash-table statistics on exit.

    u   When Remind exits, print a list of variables that were SET, but not subsequently used.

        Note that the u debugging flag may produce spurious warnings. For example, this sequence of commands:

                DEBUG +u
                SET a 1
                IFTRIG Wed
                        MSG a = [a]
                ENDIF

        will issue a warning about a being unused unless it is run on a Wednesday.

    n   Print debugging information about why Remind considers an expression to be "non-constant"

    q   Output a TRANSLATE command each time the _() built-in function is called or the %(...) substitution sequence is encountered.

-g[a|d[a|d[a|d[a|d]]]]
    Normally, reminders are issued in the order in which they are encountered in the reminder script. The -g option cause Remind to sort reminders by date and time prior to issuing them. The optional a and d characters specify the sort order (ascending or descending) for the date, time and priority fields. See the section "SORTING REMINDERS" for more information. Note that -g is ignored if you use the -n option.

-b[n]
    Set the time format for the calendar and simple-calendar outputs. N can range from 0 to 2, with the default 0. A value of 0 causes times to be inserted in 12-hour (am/pm) format. 1 causes times to be inserted in 24-hour format, and 2 inhibits the automatic insertion of times in the calendar output.

-x[n]
    Sets the iteration limit for the SATISFY clause of a REM command. Defaults to 1000.

-kcmd
    Instead of simply printing MSG-type reminders, this causes them to be passed to the specific cmd. You must use '%s' where you want the body to appear, and may need to enclose this option in quotes. Note that all shell characters in the body of the reminder are escaped with a backslash, and the entire body of the reminder is passed as a single argument. Note that this option overrides the -r option and the RUN OFF command.

    As an example, suppose you have an X Window program called xmessage that pops up a window and displays its invocation arguments. You could use:

    		remind '-kxmessage %s &' ...

    to have all of your MSG-type reminders processed using xmessage.

    A word of warning: It is very easy to spawn dozens of xmessage processes with the above technique. So be very careful. Because all shell and whitespace characters are escaped, the program you execute with the -k option must be prepared to handle the entire message as a single argument.

    If you follow the -k option with a colon, then the command is applied only to queued timed reminders. Normal reminders are handled as usual. In the above example, if you want normal reminders to simply be displayed as usual, but queued reminders to be sent to notify-send, you could use:

    		remind '-k:notify-send %s &' ...

    You use both -kcmd1 and -k:cmd2 to use different commands for queued versus non-queued reminders.

-z[n] Runs Remind in "daemon mode".  If n
    is supplied, it specifies how often (in minutes) Remind should wake up to check if the reminder script has been changed. N defaults to 1, and can range from 1 to 60. Note that the use of the -z option also enables the -f option.

    If Remind is compiled on a system that supports inotify(7), then if the reminder script supplied on the command-line is actually a directory, Remind additionally checks if all files within that directory have been modified since startup.

    If you supply the option -zj, Remind runs in a special mode called server mode. This is documented in the tkremind man page; see tkremind(1). The older server mode option -z0 still works, but is deprecated; it uses an ad-hoc method to communicate with the client rather than using JSON to communicate with the client.

-uname
    Runs Remind with the uid and gid of the user specified by name. The option changes the uid and gid as described, and sets the environment variables HOME, SHELL and USER to the home directory, shell, and user name, respectively, of the specified user. LOGNAME is also set to the specified user name. This option is meant for use in shell scripts that mail reminders to all users. Note that as of Remind 3.00.17, using -u implies -r -- the RUN directive and shell() functions are disabled. However, if you prefix name with a +-sign, then RUN and shell() are not disabled. That is, -uwhatever switches the user to whatever and disables RUN, whereas -u+whatever switches the user to whatever but leaves RUN enabled.

    Non-root users can also use the -u option. However, in this case, it only changes the environment variables as described above. It does not change the effective uid or gid.

-+username
    Causes Remind to trust files owned by the user username. Normally, if Remind reads a file that you do not own, it disables RUN and the shell() function. This option causes it to also trust files owned by username. You can supply multiple -+ options to trust multiple users, up to a limit of 20 trusted users.

-y  Causes Remind to synthesize a tag for any reminder that lacks a TAG clause.

-ivar=expr
    Sets the value of the specified var to expr, and preserves var. Expr can be any valid Remind expression. See the section "INITIALIZING VARIABLES ON THE COMMAND LINE" for more details. If you omit the =expr part, then var is initialized to 0. In other words, -ivar is exactly the same as -ivar=0.

-ifunc(args)=definition
    Allows you to define a function on the command line.

If you supply a date on the command line, it must consist of [day] month [year], where day is the day of the month, month is at least the first three letters of the English name of the month, and year is a year (all 4 digits) from 1990 to about 2075. You can leave out the day, which then defaults to 1. If you leave out the year, then it defaults to the current year. You cannot leave out the month.

If you do supply a date on the command line, then Remind uses it, rather than the actual system date, as its notion of "today." This lets you create calendars for future months, or test to see how your reminders will be triggered in the future. Similarly, you can supply a time to set Remind's notion of "now" to a particular time. Supplying a time on the command line also implicitly enables the -q option and disables the -z option. The time may be specified in 24-hour format (e.g., 13:20) or common "AM/PM" format (1:20pm).

If you would rather specify the date more succinctly, you can supply it as YYYY-MM-DD or YYYY/MM/DD. You can even supply a date and time on the command line as one argument: YYYY-MM-DD@HH:MM.

You can also specify the date as a trigger by prefixing it with the at symbol, "@". You might need to quote the argument. In this case, Remind evaluates everything after the "@" as a trigger and the resulting trigger date is used as the effective date. For example, if you want to see what reminders will trigger on the next Friday the 13th, you could use this:

    remind .reminders '@13 SATISFY [$Tw == 5]'

You can also specify the date directly and use an "@" trigger argument; in this case, Remind uses the specified date as the starting point for the trigger calculation. As an example:

    remind .reminders 2026-07-01 '@13 SATISFY [$Tw == 5]'

will set Remind's notion of "today" to 2026-11-13 because that is the first Friday the 13th on or after 2026-07-01.

In addition, you can supply a repeat parameter, which has the form *rep. This causes Remind to be run rep times, with the date incrementing on each iteration. You may have to enclose the parameter in quotes to avoid shell expansion. See the subsection "Repeated Execution" in the section "CALENDAR MODE" for more information.

LONG OPTIONS
Remind supports the following long options, which are case-sensitive:

--version
    The --version option causes Remind to print its version number to standard output and then exit.

--hide-completed-todos
    In Calendar Mode, Remind normally shows all TODOs. If you supply this option, the it will not show TODOs that have been marked as completed.

--only-todos
    Only issue TODO-type reminders.

--only-events
    Do not issue TODO-type reminders.

--json
    In Agenda Mode, output JSON instead of the normal text-mode output. --json also disables sorting (the -g option) and disables queueing (the -q option). See the section "AGENDA MODE JSON OUTPUT" for more details. The --json option is ignored in Calendar Mode. Note that in JSON mode, the output from any RUN-type reminder that would normally appear on standard output is redirected to standard error instead; this is so that RUN-type reminders don't mess up the output and cause invalid JSON to be produced on standard output.

--print-errs
    The --print-errs option causes Remind to print all possible error messages to standard output and then exit. The messages are printed in a format suitable for the first argument of a TRANSLATE command. If you TRANSLATE the error messages, then Remind will use the translated versions when outputting error and warning messages. See also TRANSLATE GENERATE in the section "THE TRANSLATION TABLE".

    Note that if an untranslated message contains printf-style formatting sequences like "%s" or "%d", then the translated message must contain the same sequences in the same order, or Remind will ignore it and use the original untranslated message.

--print-config-cmd
    This option causes Remind to print the exact ./configure command that was used when Remind was built. You can use this to build a new version of Remind using the same configuration as an existing one by running:

            eval `remind --print-config-cmd`

    from the top-level Remind source directory. (However, it's safer to simply run remind --print-config-cmd and then type in the command once you've verified that it looks OK.)

--print-tokens
    The --print-tokens option causes Remind to print the tokens used by the parser, built-in function names, and system variable names to standard output and then exit. This output is designed to make it easy to create a syntax-highlighting file for various text editors. The output can be modified by hand or by a script into a syntax-highlighting file with relative ease.

--max-execution-time=n
    Limit the total execution time (as measured by the wall clock) to n seconds. This is useful if Remind is invoked on potentially-untrustworthy files that could attempt to use a lot of resources. Note that the limit n is approximate and Remind might execute for one or two more seconds before it is killed. If n is specified as zero, then no limit is applied, just as if the option had not been used at all.

    If a limit is applied, it applies only to the foreground run of Remind. If Remind finishes processing the script and then starts handling queued reminders, the time limit is reset to no limit.

--max-expr-complexity=n
    Limit the total complexity of expression valuation for a given line in a script to n nodes. Roughly speaking, each function call, operator, constant, variable reference, etc corresponds to one expression node. By default, the limit is set to 10000000 (ten million). You can explicitly set it to zero if you don't want any limit to apply. The default limit of ten million should never be triggered by any sensible Remind script, however, and we don't recommend changing the limit.

--test
    The --test long option is only for use by the acceptance tests run by "make test". Do not use this option in production.

--flush
    The --flush long option makes Remind's standard output and standard error streams unbuffered. It is mostly used for testing and should probably not be used in production.

REMINDER FILES

Remind uses scripts to control its operation. You can use any text editor capable of creating plain-text files to create a Remind script. The commands inside a script can range from the very simple and almost immediately understandable:

        REM Mar 31 MSG International Transgender Day of Visibility

to the baroque and obscure:

        REM [date(thisyear, 1, 1) + 180] ++5 OMIT \
        sat sun BEFORE MSG [ord(thisyear-1980)] payment due %b!

A reminder file consists of commands, with one command per line. Several lines can be continued using the backslash character, as in the above example. In this case, all of the concatenated lines are treated as a single line by Remind. Note that if an error occurs, Remind reports the line number of the last line of a continued line.

Remind ignores blank lines, and lines beginning with the '#' or ';' characters. You can use the semicolon as a comment character if you wish to pass a Remind script through the C pre-processor, which interprets the '#' character as the start of a pre-processing directive.

Note that Remind processes line continuations before anything else. For example:

	# This is a comment \
	This line is part of the comment because of line continuation \
	and so on.
	REM MSG This line is not ignored (no \ above)

Remind is not case sensitive; you can generally use any mixture of upper- or lower-case for commands, parameters, invocation options, etc.

THE REM COMMAND

The most powerful command in a Remind script is the REM command. This command is responsible for issuing reminders. Its syntax is:

    REM [ONCE] [date_spec] [back] [delta] [repeat] [TODO] [MAX-OVERDUE n] [COMPLETE-THROUGH complete_date] [PRIORITY prio] [SKIP | BEFORE | AFTER] [OMIT omit_list] [ADDOMIT] [NOQUEUE] [OMITFUNC omit_function] [AT time [tdelta] [trepeat]] [SCHED sched_function] [WARN warn_function] [UNTIL expiry_date | THROUGH last_date] [SCANFROM scan_date | FROM start_date] [DURATION duration] [TAG tag] [TZ timezone] [INFO "info_string"] MSG | MSF | RUN | CAL | SATISFY | SPECIAL special | PS | PSFILE body

The parts of the REM command can be specified in any order, except that the body must come immediately after the MSG, RUN, CAL, PS, PSFILE or SATISFY keyword. The portion of the REM command before the MSG, MSF RUN, CAL or SATISFY clause is called a trigger.

In earlier versions of Remind, the REM token was optional providing that the remainder of the command cannot be mistaken for another Remind command. However, this use is deprecated and will now cause a warning to be issued. All of your reminder lines should be written to start with the REM command.

MSG, MSF, RUN, CAL, SPECIAL, PS and PSFILE

These keywords denote the type of the reminder. (SATISFY is more complicated and will be explained later.) A MSG-type reminder normally prints a message to the standard output, after passing the body through a special substitution filter, described in the section "THE SUBSTITUTION FILTER." However, if you have used the -k command-line option, then MSG-type reminders are passed to the appropriate program. Note that the options -c, -s, -p and -n disable the -k option.

Earlier versions of Remind let you omit the reminder type, in which case it defaulted to MSG. However, this usage is deprecated and will cause a warning. Something like:

	REM 6 January Dianne's Birthday

will issue the warning "Missing REM type; assuming MSG"

The MSF keyword is almost the same as the MSG keyword, except that the reminder is formatted to fit into a paragraph-like format. Three system variables control the formatting of MSF-type reminders - they are $FirstIndent, $SubsIndent and $FormWidth. They are discussed in the section "SYSTEM VARIABLES." The MSF keyword causes the spacing of your reminder to be altered - extra spaces are discarded, and two spaces are placed after periods and other characters, as specified by the system variables $EndSent and $EndSentIg. Note that if the body of the reminder includes newline characters (placed there with the %_ sequence), then the newlines are treated as the beginnings of new paragraphs, and the $FirstIndent indentation is used for the next line. You can use two consecutive newlines to have spaced paragraphs emitted from a single reminder body.

A RUN-type reminder also passes the body through the substitution filter, but then executes the result as a system command. A CAL-type reminder is used only to place entries in the calendar produced when Remind is run with the -c, -s or -p options. When Remind runs a command, it sets the command's standard input to come from /dev/null.

A PS or PSFILE-type reminder is used to pass PostScript code directly to the printer when producing PostScript calendars. This can be used to shade certain calendar entries (see the psshade() function), include graphics in the calendar, or almost any other purpose you can think of. You should not use these types of reminders unless you are an expert PostScript programmer. The PS and PSFILE reminders are ignored unless Remind is run with the -p option. See the section "More about PostScript" for more details.

A SPECIAL-type reminder is used to pass "out-of-band" information from Remind to a calendar-producing back-end. It should be followed by a word indicating the type of special data being passed. The type of a special reminder depends on the back-end. For the Rem2PS back-end, SPECIAL PostScript is equivalent to a PS-type reminder, and SPECIAL PSFile is equivalent to a PSFILE-type reminder. The body of a SPECIAL reminder is obviously dependent upon the back-end. A back-end must ignore a SPECIAL that it does not recognize.

DATE SPECIFICATIONS

A date_spec consists of zero to four parts. These parts are day (day of month), month (month name), year and weekday. Month and weekday are the English names of months and weekdays. At least the first three characters must be used. The following are examples of the various parts of a date_spec:

day:
    1, 22, 31, 14, 3

month:
    JANUARY, feb, March, ApR, may, Aug

year:
    1990, 1993, 2030. The year can range from 1990 to 2075.

weekday:
    Monday, tue, Wed, THU, Friday, saturday, sundAy

Note that there can be several weekday components separated by spaces in a date_spec.

INTERPRETATION OF DATE SPECIFICATIONS

The following examples show how date specifications are interpreted.

1. Null date specification - the reminder is triggered every day. The trigger date for a specific run is simply the current system date. For example:

        REM MSG This is triggered every time Remind runs

2. Only day present. The reminder is triggered on the specified day of each month. The trigger date for a particular run is the closest such day to the current system date. For example:

	REM 1 MSG First of every month.
	REM 31 MSG 31st of every month that has 31 days.

3. Only month present. The reminder is triggered every day of the specified month. Example:

	REM Feb MSG Every day in February

4. day and month present. Examples:

	REM 6 Jan MSG Every 6th of January
	REM Feb 29 MSG Every 29th of February

5. Only year present. Example:

	REM 1991 MSG Every day in 1991

6. year and day present. Examples:

	REM 1 1990 MSG 1st of every month in 1990
	REM 1992 23 MSG 23rd of every month in 1992

7. year and month present. Examples:

	REM Feb 1991 MSG Every day in Feb 1991
	REM 1992 September MSG Every day in Sept 1992

8. year, month and day present. Examples:

	REM 8 Jan 1991 MSG 8th January 1991.
	REM 1992 March 9 MSG 9th March 1992.

9. weekday only. Examples:

	REM Sat MSG Every Saturday
	REM Mon Tue Wed Thu Fri MSG Every working day
	REM Monday Wednesday MSG Every Monday and Wednesday

10. weekday and day present. Examples:

	REM Sat 1 MSG First Saturday of every month
	REM Mon Tue Wed Thu Fri 15 \
		MSG 1st working day on or after 15th of every month

11. weekday and month present. Examples:

	REM Mon March MSG Every Monday in March
	REM Mon Tue Wed Thu Fri Feb MSG Every working day in February

12. weekday, month and day present. Examples:

	REM Mon 1 March MSG First Monday in March
	REM Sat Sun 15 July MSG First Sat or Sun on or after 15 July

13. weekday and year present. Example:

	REM Sat Sun 1991 MSG Every Saturday and Sunday in 1991

14. weekday, day and year present. Examples:

	REM Mon 15 1990 MSG 1st Mon after 15th of every month in 1990
	REM Mon Tue Wed Thu Fri 1 1990 \
		MSG 1st working day of every month in 1990

15. weekday, month and year present. Example:

	REM Mon Wed 1991 Feb MSG Every Mon and Wed in Feb 1991.

16. weekday, day, month and year present. Example:

	REM Mon Tue Wed Thu Fri 28 Oct 1990 \
		MSG 1st working day on or after 28 October 1990.

Note that when both weekday and day are specified, Remind chooses the first date on or after the specified day that also satisfies the weekday constraint. It does this by picking the first date on or after the specified day that is listed in the list of weekdays. Thus, a reminder like:

	REM Mon Tue 28 Oct 1990 MSG Hi

would be issued only on Monday, 29 October, 1990. It would not be issued on Tuesday, 30 October, 1990, since the 29th is the first date to satisfy the weekday constraints.

SHORT-HAND DATE SPECIFICATIONS

In addition to spelling out the day, month and year separately, you can specify YYYY-MM-DD or YYYY/MM/DD. For example, the following statements are equivalent:

	REM 5 June 2010 MSG Cool!
	REM 2010-06-05  MSG Cool!

You can also specify a date and time as YYYY-MM-DD@HH:MM. These statements are equivalent:

	REM 19 Dec 2010 AT 16:45 MSG Hi
	REM 2010-12-19@16:45 MSG Hi

There's one subtlety with short-hand date specifications: The following statements are not equivalent:

	REM 19 Dec 2010 AT 16:45 +60 MSG Hi
	REM 2010-12-19@16:45 +60 MSG Hi

In the second statement, the "+60" is a delta that applies to the date rather than a tdelta that applies to the time. We recommend explicitly using the AT keyword with timed reminders.

THE REMIND ALGORITHM

Remind uses the following algorithm to compute a trigger date: Starting from the current date, it examines each day, one at a time, until it finds a date that satisfies the date specification, or proves to itself that no such date exists. (Actually, Remind merely behaves as if it used this algorithm; it would be much too slow in practice. Internally, Remind uses much faster techniques to calculate a trigger date.) See DETAILS ABOUT TRIGGER COMPUTATION for more information.

BACKWARD SCANNING

Sometimes, it is necessary to specify a date as being a set amount of time before another date. For example, the last Monday in a given month is computed as the first Monday in the next month, minus 7 days. The back specification in the reminder is used in this case:

	REM Mon 1 -7 MSG Last Monday of every month.

A back is specified with one or two dashes followed by an integer. This causes Remind to move "backwards" from what would normally be the trigger date. The difference between --7 and -7 will be explained when the OMIT keyword is described.

ADVANCE WARNING

For some reminders, it is appropriate to receive advance warning of the event. For example, you may wish to be reminded of someone's birthday several days in advance. The delta portion of the REM command achieves this. It is specified as one or two "+" signs followed by a number n. Again, the difference between the "+" and "++" forms will be explained under the OMIT keyword. Remind will trigger the reminder on computed trigger date, as well as on each of the n days before the event. Here are some examples:

	REM 6 Jan +5 MSG Remind me of birthday 5 days in advance.

The above example would be triggered every 6th of January, as well as the 1st through 5th of January.

PERIODIC REMINDERS

We have already seen some built-in mechanisms for certain types of periodic reminders. For example, an event occurring every Wednesday could be specified as:

	REM Wed MSG Event!

However, events that do not repeat daily, weekly, monthly or yearly require another approach. The repeat component of the REM command fills this need. To use it, you must completely specify a date (year, month and day, and optionally weekday); this is the start date of the repetition period. The repeat component is an asterisk followed by a number specifying the repetition period in days.

For example, suppose you get paid every second Wednesday, and your last payday was Wednesday, 28 October, 1992. You can use:

	REM 28 Oct 1992 *14 MSG Payday

This issues the reminder every 14 days, starting from 28 Oct 1992. You can use delta and back with repeat. Note, however, that the back is used only to compute the starting date; thereafter, the reminder repeats with the specified period. Similarly, if you specify a weekday, it is used only to calculate the starting date, and does not affect the repetition period.

SCANFROM and FROM

The SCANFROM and FROM keywords are for advanced Remind programmers only, and will be explained in the section "DETAILS ABOUT TRIGGER COMPUTATION" near the end of this manual. Note that SCANFROM is available only in versions of Remind from 03.00.04 up. FROM is available only from 03.01.00 and later.

PRIORITY

The PRIORITY keyword must be followed by a number from 0 to 9999. It is used in calendar mode and when sorting reminders. If two reminders have the same trigger date and time, then they are sorted by priority. If the PRIORITY keyword is not supplied, a default priority of 5000 is used. (This default can be changed by adjusting the system variable $DefaultPrio. See the section "SYSTEM VARIABLES" for more information.)

EXPIRY DATES

Some reminders should be issued periodically for a certain time, but then expire. For example, suppose you have a class every Friday, and that your last class is on 11 December 1992. You can use:

	REM Fri UNTIL 11 Dec 1992 MSG Class today.

Another example: Suppose you have jury duty from 30 November 1992 until 4 December 1992. The following reminder will issue the message every day of your jury duty, as well as 2 days ahead of time:

	REM 1992-11-30 *1 +2 UNTIL 1992-12-04 MSG Jury duty

Note that the repeat of *1 is necessary; without it, the reminder would be issued only on 30 November (and the two days preceding.)

As a special case, you can use the THROUGH keyword instead of *1 and UNTIL. The following two REM commands are equivalent:

	REM 1992-11-30 *1 +2 UNTIL 1992-12-04 MSG Jury duty
	REM 1992-11-30 +2 THROUGH 1992-12-04 MSG Jury duty

If you have an expiry date via the use of THROUGH or UNTIL, then Remind will never trigger the reminder after the expiry date. For example, if you have this:

        OMIT 2021-01-08
        REM 2021-01-01 THROUGH 2021-01-08 AFTER MSG Test

the reminder will not be triggered on 2021-01-08, and nor will it be triggered on 2021-01-09; even though the AFTER keyword would normally move the 8th's reminder to the 9th, the expiry date of 2021-01-08 overrides that.

THE ONCE KEYWORD

Sometimes, it is necessary to ensure that reminders are run only once on a given day. For example, compare the following two reminders:

        REM Fri RUN do_backup
        REM Fri ONCE RUN do_backup

The first will be run every time you invoke Remind on a Friday, whereas the second will be run only the first time you invoke Remind on a given Friday.

If you run Remind from your .login script, for example, and log in several times per day, the do_backup program in the first reminder will be run each time you log in. If, however, you use the ONCE keyword in the reminder, the Remind checks the last access date of the reminder script. If it is the same as the current date, Remind assumes that it has already been run, and will not issue reminders containing the ONCE keyword.

Note that if you view or edit your reminder script, the last access date will be updated, and the ONCE keyword will not operate properly. You can fix this by setting a timestamp file for Remind to track the last-run date; see the documentation of $OnceFile in the SYSTEM VARIABLES section. If you use standard input as your Remind input file, then you must use $OnceFile for the ONCE keyword to work properly.

If you start Remind with the -o option, then the ONCE keyword will be ignored and any $OnceFile will be ignored.

LOCALLY OMITTING WEEKDAYS

The OMIT portion of the REM command is used to "omit" certain days when counting the delta or back. It is specified using the keyword OMIT followed by a list of weekdays. Its action is best illustrated with examples:

	REM 1 +1 OMIT Sat Sun MSG Important Event

This reminder is normally triggered on the first of every month, as well as the day preceding it. However, if the first of the month falls on a Sunday or Monday, then the reminder is triggered starting from the previous Friday. This is because the delta of +1 does not count Saturday or Sunday when it counts backwards from the trigger date to determine how much advance warning to give.

Contrast this with the use of "++1" in the above command. In this case, the reminder is triggered on the first of each month, as well as the day preceding it. The omitted days are counted.

	REM 1 -1 OMIT Sat Sun MSG Last working day of month

Again, in the above example, the back of -1 normally causes the trigger date to be the last day of the month. However, because of the OMIT clause, if the first of the month falls on a Sunday or Monday, the trigger date is moved backwards past the weekend to Friday. (If you have globally omitted holidays, the reminder will be moved back past them, also. See "The OMIT command" for more details.)

By comparison, if we had used "--1", the reminder would be triggered on the last day of the month, regardless of the OMIT.

If you locally omit weekdays but also have globally-omitted weekdays, then the list of omitted weekdays is the union of the two. Consider this example:

        OMIT Sat Sun
        REM 15 OMIT Fri Sat MSG Whatever

In the REM command, the effective list of omitted weekdays will be Friday, Saturday and Sunday.

COMPUTED LOCAL OMITS

The OMITFUNC phrase of the REM command allows you to supply a function that determines whether or not a date is omitted. Note that OMITFUNC must be given just the name of a user-defined function; it can't take an arbitrary expression or the name of a built-in function.

The function is passed a single parameter of type DATE, and must return a non-zero integer if the date is considered "omitted" and 0 otherwise. Here's an example:

        FSET _third(x) (day(x) % 3) || \
                       (wkdaynum(x) == 0) || \
                       (wkdaynum(x) == 6)
        REM OMITFUNC _third AFTER MSG Working day divisible by 3

In the example above, the reminder is triggered every Monday to Friday whose day-of-month number is divisible by three. Here's how it works:

o   The OMITFUNC _third portion causes all days for which _third(x) returns non-zero to be considered "omitted". This causes all days whose day-of-month number is not a multiple of three to be omitted. Note that _third also returns non-zero if the weekday is Sunday or Saturday.

o   The AFTER keyword causes the reminder to be moved after a block of omitted days.

The combination of OMITFUNC and AFTER keyword causes the reminder to be issued on all days whose day-of-month number is divisible by three, but not on Saturday or Sunday.

Note that if you use OMITFUNC, then a local OMIT is ignored as are all global OMITs. If you want to omit specific weekdays, your omit function will need to test for them specifically. If you want to take into account the global OMIT context, then your omit function will need to test for that explicitly (using the isomitted() function.)

Note that an incorrect OMITFUNC might cause all days to be considered omitted. For that reason, when Remind searches through omitted days, it terminates the search after the SATISFY iteration limit (command-line option -x.)

ADDING TRIGGER DATES TO THE OMIT CONTEXT

If the ADDOMIT keyword appears in a REM command, then the trigger date (if one could be calculated) is automatically added to the list of global OMITs.

The command:

        REM ... whatever ... ADDOMIT MSG Foo

is identical in behavior to the sequence:

        REM ... whatever ... SATISFY 1
        IF trigvalid()
            OMIT [trigdate()] MSG Foo
        ENDIF

TIMED REMINDERS

Timed reminders are those that have an AT keyword followed by a time and optional tdelta and trepeat. The time may be specified in 24-hour format, with 0:00 representing midnight, 12:00 representing noon, and 23:59 representing one minute to midnight. Alternatively, it may be specified in common "AM/PM" format; in this case, the hour must range from 1 to 12. 12:00am represents midnight, 12:00pm represents noon, and 11:59pm represents one minute to midnight. The "am" and "pm" portions are case-insensitive and the "m" is optional.

You can use either a colon or a period to separate the hours from the minutes. That is, 13:39 and 13.39 are equivalent.

Remind treats timed reminders specially. If the trigger date for a timed reminder is the same as the current system date, the reminder is queued for later activation. When Remind has finished processing the reminder file, it puts itself in the background, and activates timed reminders when the system time reaches the specified time. Note that if you use the NOQUEUE modifier in the REM command, then this queuing and background activation is not performed. NOQUEUE is useful if you want a time to be associated with a reminder (e.g., in the calendar) but are not interested in a popup reminder happening at the specified time.

If you use a very large tdelta, then Remind will queue future-dated reminders whose tdelta and optional trep would cause them to be issued today.

However, if you use the SCHED keyword, then any tdelta is ignored and you cannot force the reminder to be queued earlier than the actual trigger date.

For example, the following reminder, triggered every working day, will emit a message telling you to leave at 5:00pm:

	REM Mon Tue Wed Thu Fri AT 17:00 MSG Time to leave!

The following reminder will be triggered on Thursdays and Fridays, but will only be queued on Fridays:

	REM Fri ++1 AT 1:00PM MSG Lunch at 1pm Friday.

The tdelta and trepeat have the same form as a repeat and delta, but are specified in minutes. For example, this reminder will be triggered at 12:00pm as well as 45 minutes before:

	REM AT 12:00 +45 MSG Example

The following will be issued starting at 10:45, every half hour until 11:45, and again at noon.

	REM AT 12:00 +75 *30 MSG Example2

The "+75" means that the reminder is issued starting 75 minutes before noon; in other words, at 10:45. The *30 specifies that the reminder is subsequently to be issued every 30 minutes. Note that the reminder is always issued at the specified time, even if the tdelta is not a multiple of the trepeat. So the above example is issued at 10:45am, 11:15am, 11:45am, and 12:00pm. Note that in the time specification, there is no distinction between the "+" and "++" forms of tdelta.

Normally, Remind will issue timed reminders as it processes the reminder script, as well as queuing them for later. If you do not want Remind to issue the reminders when processing the script, but only to queue them for later, use the -a command-line option. If you do not want reminders to be queued for later, use the -q command-line option.

Normally, Remind forks a background process to handle queued reminders. If you want Remind to remain in the foreground, use the -f command-line option. This is useful, for example, in .xinitrc scripts, where you can use the command:

	remind -fa myreminders &

This ensures that when you exit X-Windows, the Remind process is killed.

WARNING ABOUT TIMED REMINDERS

Note: If you use user-defined functions or variables (described later) in the bodies of timed reminders, then when the timed reminders are activated, the variables and functions have the definitions that were in effect at the end of the reminder script. These definitions may not necessarily be those that were in effect at the time the reminder was queued. In addition, the OMIT context is whatever was in effect at the end of the reminder script, which may not necessarily be the same as when the REM command was first processed.

THE SCHED AND WARN KEYWORDS

The SCHED keyword allows more precise control over the triggering of timed reminders, and the WARN keyword allows precise control over the advance triggering of all types of reminders. However, discussion must be deferred until after expressions and user-defined functions are explained. See the subsection "PRECISE SCHEDULING" further on.

TAG, INFO AND DURATION

The TAG keyword lets you "tag" certain reminders. This facility is used by certain back-ends or systems built around Remind, such as TkRemind. These back-ends have specific rules about tags; see their documentation for details.

The TAG keyword is followed by a tag consisting of up to 48 characters. You can have as many TAG clauses as you like in a given REM statement. A tag can contain any character except for whitespace and a comma.

If you supply the -y option to Remind, then any reminder that lacks a TAG will have one synthesized. The synthesized tag consists of the characters "__syn__" followed by the hexadecimal representation of the MD5 sum of the REM command line. This lets you give a more-or-less unique identifier to each distinct REM command.

The INFO keyword is similar to TAG but is intended to convey metadata about an event, such as its location. Back-ends will have their own rules about which info_strings they recognize, and must ignore info_strings they don't recognize. Note that INFO must be followed by a quoted string; you can include newlines in the string by supplying them as "\n".

An INFO string must be of the form "Header: Value". The header can consist of any printable character, but cannot contain whitespace. The value can consist of any characters you like. Space may not appear before the colon, but can appear afterwards; such space is not considered to be part of the value. If there is more than one INFO string for a given reminder, there cannot be any duplicate headers. Case is ignored when determining if a header is a duplicate of an existing one.

For example, a hypothetical back-end might let you set the location and description of a reminder like this:

        REM 26 Feb 2025 INFO "Location: Boardroom #2" \
                        INFO "Description: Go over latest pull requests" \
                        MSG Engineering meeting

While back-ends can choose which INFO strings to support, all back-ends should endeavor to support three standard ones: Location:, Description: and Url:. TkRemind supports all three of these, turning reminders with a Url: INFO string into hyper-links, and popping up information windows for the Location: and Description: INFO strings. Location: and Url: are self-explanatory; Description: is meant for a longer, more in-depth description of the reminder than the summary that is normally displayed.

The DURATION keyword makes sense only for timed reminders; it specifies the duration of an event. For example, if you have a 90-minute meeting starting at 1:00pm, you could use any of the following:

        REM 5 March 2021 AT 13:00 DURATION 1:30 MSG Meeting
        REM 5 March 2021 AT 13:00 DURATION 90 MSG Meeting
        REM 5 March 2021 AT 1:00pm DURATION 1:30 MSG Meeting
        REM 5 March 2021 AT 1:00pm DURATION 90 MSG Meeting

For long-duration reminders, it is convenient to use expressions to simplify writing the DURATION. For example, if you are away from 20 Feb 2023 through 23 Feb 2023 (a total of 4 days) you could write:

        REM 20 Feb AT 00:00 DURATION [4*24]:00 MSG away
        REM 20 Feb AT 00:00 DURATION [4*24*60] MSG away

Note that duration is specified either as hours:minutes or just as minutes specified as an integer.

If you specify a duration of 00:00 or 0, then Remind behaves exactly as if no DURATION at all had been present. Although durations specified as hours:minutes look superficially like a time-of-day, they are not; the hours component is not limited to the range 00-23.

SYNTACTIC SUGAR FOR REM

The REM command has syntactic sugar to let you express common reminders. The following pairs of reminders are equivalent:

        REM First Monday April MSG Foo
        REM Mon 1 April        MSG Foo
        REM Second Monday May  MSG Bar
        REM Mon 8 May          MSG Bar
        REM Third Monday MSG Third Monday of every month
        REM Mon 15 MSG Third Monday of every month
        REM Fourth Sunday June 2025 MSG Fourth Sunday in June 2025
        REM Sun 22 June 2025 MSG Fourth Sunday in June 2025
        REM Last Monday MSG Last Monday of every month
        REM Mon 1 --7 MSG Last Monday of every month
        REM Last Monday April MSG Last Monday of every April
        REM Mon 1 May --7 MSG  Last Monday of every April
        REM Last Monday December 2025 MSG Last Monday of Dec 2025
        REM Monday 1 Jan 2026 --7 MSG Last Monday of Dec 2025

Note that Last effectively adjusts the month and year, if necessary, to make the reminder trigger on the correct date.

The keyword IN is completely ignored, so you can write (for example):

        REM Second Monday in May MSG foo
        REM Last Monday in December 2025 MSG Bar

An alternate form of back makes writing reminders easier. The following groups of reminders are equivalent:

        REM ~~1 MSG Last day of every month
        REM Lastday MSG  Last day of every month
        REM 1 --1 MSG Last day of every month
        REM May ~~1 MSG Last day of May
        REM Lastday May MSG Last day of May
        REM 1 June --1 MSG Last day of May
        REM Dec 2025 ~~1 MSG Last day of December 2025
        REM Lastday Dec 2025 MSG Last day of December 2025
        REM 1 Jan 2026 --1 MSG Last day of December 2025
        REM Apr ~1 OMIT SAT SUN MSG Last workday of April
        REM Lastworkday April OMIT SAT SUN MSG Last workday of April
        REM 1 May -1 OMIT SAT SUN MSG Last workday of April
        REM Apr ~~7 MSG Seventh-last day of April
        REM 1 May --7 MSG Seventh-last day of April
        REM Apr ~2 OMIT SAT SUN MSG Second-last workday of April
        REM 1 May -2 OMIT SAT SUN MSG Second-last workday of April

As we see, "Lastday" is equivalent to ~~1 and "Lastworkday" to ~1.

Note that the First/Second/Third/Fourth/Last keywords and the ~ and ~~ form of back imply a value for the day of the month; as such, they cannot be combined with a day. Additionally, First/Second/Third/Fourth/Last must have at least one weekday name. The following are illegal:

        REM First Monday 3 June MSG Huh?
        REM April 3 ~~1 MSG What?
        REM Second June MSG Where's the weekday???

THE SUBSTITUTION FILTER

Before being processed, the body of a REM command is passed through a substitution filter. The filter scans for sequences "%x" (where "x" is any letter and certain other characters) and performs substitutions as shown below. (All dates refer to the trigger date of the reminder.)

%a  is replaced with "on weekday, day month, year"
    For example, consider the reminder:

    REM 18 Oct 1990 +4 MSG Meeting with Bob %a.

    On 16 October 1990, it would print "Meeting with Bob on Thursday, 18 October, 1990."

    On 17 October 1990, it would print "Meeting with Bob tomorrow."

    On 18 October 1990, it would print "Meeting with Bob today."

%b  is replaced with "in diff day's time" where diff is the actual number of days between the current date and the trigger date. (OMITs have no effect.)
    For example, consider:

    REM 18 Oct 1990 +4 MSG Meeting with Bob %b.

    On 16 October 1990, it would print "Meeting with Bob in 2 days' time."

    On 17 October 1990, it would print "Meeting with Bob tomorrow."

    On 18 October 1990, it would print "Meeting with Bob today."

%c  is replaced with "on weekday"
    Example: REM 18 Oct 1990 +4 MSG Meeting with Bob %c.

    On 16 October 1990, it would print "Meeting with Bob on Thursday."

    On 17 October 1990, it would print "Meeting with Bob tomorrow."

    On 18 October 1990, it would print "Meeting with Bob today."

%d  is replaced with "day", the day of the month.

%e  is replaced with "on dd-mm-yyyy"

%f  is replaced with "on mm-dd-yyyy"

%g  is replaced with "on weekday, day month"

%h  is replaced with "on dd-mm"

%i  is replaced with "on mm-dd"

%j  is replaced with "on weekday, month day-th, year" This form appends the characters "st", "nd", "rd" or "th" to the day of the month, as appropriate.

%k  is replaced with "on weekday, month day-th"

%l  is replaced with "on yyyy-mm-dd"

%m  is replaced with "month", the name of the month.

%n  is replaced with the number (1 to 12) of the month.

%o  is replaced with " (today)" if and only if the current system date is the same as the date being used by Remind as the current date. Recall that you can specify a date for Remind to use on the command line. This substitution is not generally useful in a REM command, but is useful in a BANNER command. (See "The BANNER Command.")

%p  is replaced with "s" if the diff between the current date and the trigger date is not 1. You can use this to construct reminders like:
    REM 1 Jan +4 MSG %x day%p to go before New Year!

%q  is replaced with "'s" if the diff between the trigger date and the current date is 1. Otherwise, it is replaced with "s'" This can be used as follows:
    REM 1 Jan +4 MSG New Year in %x day%q time!

%r  is replaced with the day of the month (01 to 31) padded with a leading zero if needed to pad to two digits.

%s  is replaced with "st", "nd", "rd" or "th" depending on the day of the month.

%t  is replaced with the number of the month (01 to 12) padded to two digits with a leading zero.

%u  is replaced with "on weekday, day-th month, year" This is similar to %a except that "st", "nd", "rd" or "th" is added to the day as appropriate.

%v  is replaced with "on weekday, day-th month"

%w  is replaced with "weekday", the name of the day of the week.

%x  is replaced with the diff between the current date and the trigger date. The diff is defined as the actual number of days between these two dates; OMITs are not counted. (Strict date subtraction is performed.)

%y  is replaced with "year", the year of the trigger date.

%z  is replaced with "yy", the last two digits of the year.

%(any_text)
    is replaced with the lookup of any_text in the translation table. It is the equivalent of [_("any_text")] but is more convenient to type.

%<any_text>
    is replaced with the INFO value associated with the header any_text or the empty string if no such INFO value exists. It is the equivalent of [triginfo("any_text")] but is more convenient to type.

%_  (percent-underscore) is replaced with a newline. You can use this to achieve multi-line reminders. Note that calendar back-ends vary in how they handle multi-line reminders:

    o   Running remind -c preserves newlines in the terminal calendar output.

    o   rem2pdf preserves newlines if remind is invoked with the -pp or -ppp option.

    o   rem2html preserves newlines if remind is invoked with the -pp option.

    o   tkremind preserves newlines.

    o   rem2ps converts newlines to spaces. But rem2ps is deprecated; use rem2pdf instead.

    o   The "simple calendar" formats (i.e., remind's -s, -n and -p options) convert newlines to spaces.

    All calendar back-ends collapse multiple spaces to a single space and multiple newlines to a single newline.

%1  is replaced with "now", "m minutes from now", "m minutes ago", "h hours from now", "h hours ago", "h hours and m minutes from now" or "h hours and m minutes ago", as appropriate for a timed reminder. If the reminder is more than a day in the future, then the phrase will be prefixed by "d days,". Note that unless you specify the -a option, timed reminders will be triggered like normal reminders, and thus a timed reminder that occurred earlier in the day may be triggered. This causes the need for the "...ago" forms.

%2  is replaced with "at hh:mmam" or "..pm" depending on the AT time of the reminder.

%3  is replaced with "at hh:mm" in 24-hour format.

%4  is replaced with "mm" where mm is the number of minutes between "current" and the trigger date and time specified by AT. If the AT time is earlier than the current time, then the result is negative.

%5  is replaced with "ma" where ma is the absolute value of the number produced by %4.

%6  is replaced with "ago" or "from now", depending on the relationship between the AT time and the current time.

%7  is replaced with the number of hours between the AT time and the current time. It is always non-negative and always between 0 and 23. (That is, for events more than a day away, the days are not counted in %7.)

%8  is replaced with the number of minutes between the AT time and the current time, after the hours (%7) have been subtracted out. This is a number ranging from 0 to 59.

%9  is replaced with "s" if the value produced by %8 is not 1.

%0  is replaced with "s" if the value produced by %7 is not 1.

%!  is replaced with "is" if the current date and time is before the trigger date and the AT time, or "was" if it is after. The %! sequence may be used in a non-timed reminder, in which case only dates are compared.

%?  is replaced with "are" if the current date and time is before the trigger date and the AT time, or "were" if it is after. The %? sequence may be used in a non-timed reminder, in which case only dates are compared.

%@  is similar to %2 but displays the current time.

%#  is similar to %3 but displays the current time.

%:  is replaced with " (done)" for a TODO reminder whose trigger date is on or after its COMPLETE-THROUGH date. It is replaced with the empty string in any other situation. Note that because Remind does not display completed TODO reminders in Agenda Mode, this escape sequence is really only useful in Calendar Mode.

%"  (percent-doublequote) is removed. This sequence is not used by the substitution filter, but is used to tell Remind which text to include in a calendar entry when the -c, -s or -p option is chosen. See "CALENDAR MODE"

Notes:

o   Remind normally prints a blank line after each reminder; if the last character of the body is "%", the blank line will not be printed. You can globally suppress the extra blank lines by setting $AddBlankLines to 0.

o   Substitutions a, b, c, e, f, g, h, i, j, k, l, u and v all are replaced with "today" if the current date equals the trigger date, or "tomorrow" if the trigger date is one day after the current date. Thus, they are not the same as substitutions built up from the simpler %w, %y, etc. sequences.

o   The a, c, e, f, g, h, i, j, k, l, u, v, 2, and 3 substitutions may be preceded by an asterisk (for example, %*c) which causes the word "at" or "on" that would normally be included in the output to be omitted.

o   The ! and ? substitutions may be preceded by an asterisk (%*! or %*?), in which case the comparison is made between the trigger date and realtoday() instead of today().

o   Any of the substitutions dealing with time (0 through 9) produce undefined results if used in a reminder that does not have an AT keyword. Also, if a reminder has a delta and may be triggered on several days, the time substitutions ignore the date. Thus, the %1 substitution may report that a meeting is in 15 minutes, for example, even though it may only be in 2 days time, because a delta has triggered the reminder. It is recommended that you use the time substitutions only in timed reminders with no delta that are designed to be queued for timed activation.

o   Capital letters can be used in the substitution sequence, in which case the first character of the substituted string is capitalized (if it is normally a lower-case letter.)

o   All other characters following a "%" sign are simply copied. In particular, to get a "%" sign out, use "%%" in the body. To start the body of a reminder with a space, use "% ", since Remind normally scans for the first non-space character after a MSG, CAL or RUN token.

EVENTS AND TODOS

The REM command is normally used to create an EVENT. This is something that happens at a certain time, possibly recurring, and happens no matter what action you take. Events include things like birthdays, holidays, meetings, etc... pretty much everything that occurs on a particular schedule. Once the date of an event has passed, Remind will no longer remind you about the event.

A TODO is different; it is a task that you have to complete by a specific date or date and time. If you don't explicitly mark a TODO as done, Remind will keep reminding you about it even past the due date..

To mark a REM as a TODO, simply include the TODO keyword. For example:

    REM TODO 15 August 2025 ++5 MSG Buy cat food %b.

In Agenda Mode, Remind will start warning you on 10 Aug 2025 that you have to buy cat food in 5 days' time, 4 days' time, etc...

However, on 16 Aug 2025, Remind will say "Buy cat food yesterday." and it will keep reminding you of your need to buy cat food until the end of time, or until you mark the TODO as done.

MARKING TODOS AS DONE

There are two ways to mark a TODO as done. If the TODO is not recurring, the simplest way is simply to remove the TODO designator from the REM command (or indeed, to completely delete it.) The former keeps the reminder on the calendar while the latter completely removes it.

If a TODO is recurring, use the COMPLETE-THROUGH clause to mark which recurrences have been completed. For example:

    REM TODO 30 April ++15 COMPLETE-THROUGH 2025-04-30 MSG File taxes

Canadian income taxes must be filed every 30 April. The above command will remind you to pay taxes in 2026. If you don't update the COMPLETE-THROUGH date, then after 30 April 2026, Remind will keep reminding you until the end of time that your taxes were due on 30 April 2026. To indicate that you've paid them, simply update the COMPLETE-THROUGH date to 2026-04-30 and then Remind will start reminding you of your 2027 taxes (starting 15 days before the due date.)

It is an error to specify COMPLETE-THROUGH without also specifying TODO. The keyword COMPLETED-THROUGH may be used as a synonym for COMPLETE-THROUGH.

LIMITING REMINDERS ABOUT OVERDUE TODOS

Although Remind is happy to keep reminding you about overdue TODOs for hundreds of years, for some things this may be pointless. If you want Remind to stop nagging you about an overdue TODO after a certain number of days, use the MAX-OVERDUE n clause. In this case, Remind stops reminding you of a TODO that is overdue by more than n days. Here is an example.

    REM TODO 2025-08-13 ++5 MAX-OVERDUE 5 MSG Task: %b.

Remind starts reminding you of the task on 2025-08-08, because of the ++5 back value. It keeps reminding you of the task after the due date. However, the last time it will remind you will be on 2025-08-18, because of the MAX-OVERDUE clause. Starting on 2025-08-19, Remind will no longer remind you of the task since it's probably pointless---it has passed the MAX-OVERDUE period.

MORE DETAILS ABOUT TODOS

TODOs are treated specially only in Agenda Mode. In Calendar Mode, they appear in the calendar exactly as a normal event would.

TODOs are implemented internally by using the COMPLETE-THROUGH date plus one day as the starting point for Remind's date-scanning algorithm. If you have a recurring TODO without a COMPLETE-THROUGH clause, then Remind starts scanning from the beginning of time, which we all know is 1 January 1990. Consider this command:

    REM TODO Wed +7 MSG Take out the trash %a (%b)

Running that command in Agenda Mode on 2025-08-13 yields the following output:

    Take out the trash on Wednesday, 3 January, 1990 (13006 days ago)

Remind is very persistent about reminding you of tasks! If you take out the trash and mark it done:

    REM TODO Wed +7 COMPLETE-THROUGH 2025-08-13 MSG Take out the trash %a (%b)

then you get this:

    Take out the trash on Wednesday, 20 August, 2025 (in 7 days' time)

You can use FROM and UNTIL to limit the recurrence interval of tasks just as you can with events. For example, if you are house-sitting for the month of August and need to water plants every Wednesday:

    REM TODO Wed +7 FROM 2025-08-06 UNTIL 2025-08-27 MSG Plants %b.

Running that command on 13 Aug yields: "Plants 7 days ago." because you have not told Remind that you completed the first watering. If you finish your duties and add a COMPLETE-THROUGH date of 2025-08-27, then Remind never reminds you of that task in the future.

In Purge Mode, Remind will not purge TODOs unless they have been marked as complete. In the case of a recurring TODO, Remind will not purge it until the last occurrence is marked as complete.

THE OMIT COMMAND

In addition to being a keyword in the REM command, OMIT is a command in its own right. Its syntax is:

    OMIT weekday [weekday...]

    or:

    OMIT [day] month [year]

    or:

    OMIT [day1] month1 [year1] THROUGH [day2] month2 [year2]

The OMIT command is used to "globally" omit certain days (usually holidays). These globally-omitted days are skipped by the "-" and "+" forms of back and delta, but not by the "--" and "++" forms. Some examples:

    OMIT Saturday Sunday
    OMIT 1 Jan
    OMIT 7 Sep 1992
    OMIT 15 Jan THROUGH 14 Feb
    OMIT May     # Equivalent to OMIT May 1 THROUGH May 31
    OMIT 25 Dec THROUGH 4 Jan
    OMIT 2023-05-03 THROUGH 2023-05-12
    OMIT Jun THROUGH July  # Equivalent to OMIT Jun 1 THROUGH July 31

The first example omits every Saturday and Sunday. This is useful for reminders that shouldn't trigger on weekends.

The second example specifies a holiday that occurs on the same date each year - New Year's Day.

The third example specifies a holiday that changes each year - Labour Day. For these types of holidays, you must create an OMIT command for each year. (Later, in the description of expressions and some of the more advanced features of Remind, you will see how to automate this for some cases.)

As with the REM command, you can use shorthand specifiers for dates; the following are equivalent:

	OMIT 7 Sep 1992
	OMIT 1992-09-07

For convenience, you can use a delta and MSG or RUN keyword in the OMIT command. The following sequences are equivalent:

	OMIT 1 Jan
	REM 1 Jan +4 MSG New year's day is %b!
	and
	OMIT 1 Jan +4 MSG New year's day is %b!

The THROUGH keyword lets you conveniently OMIT a range of days. For example, the following sequences are equivalent:

	OMIT 3 Jan 2011
	OMIT 4 Jan 2011
	OMIT 5 Jan 2011
	and
	OMIT 3 Jan 2011 THROUGH 5 Jan 2011

Note that Remind has a compiled-in limit to the number of full OMITs. If you omit a range of N fully-specified (i.e., year included) days, then N full OMITs are used up. Trying to omit a very large range may result in the error "Too many full OMITs"

You can make a THROUGH OMIT do double-duty as a REM command as long as both dates are fully specified

	OMIT 6 Sep 2010 THROUGH 10 Sep 2010 MSG Vacation

If you use a THROUGH clause, then either the year must be supplied before and after the THROUGH, or it must be missing before and after the THROUGH. The following are legal:

    OMIT 25 Dec THROUGH 6 Jan
    OMIT 25 Dec 2024 THROUGH 6 Jan 2025

But the following are not:

    OMIT 25 Dec THROUGH 6 Jan 2025
    OMIT 25 Dec 2024 THROUGH 6 Jan

You can debug your global OMITs with the following command:

	OMIT DUMP

The OMIT DUMP command prints the current global omits to standard output.

THE BEFORE, AFTER AND SKIP KEYWORDS

Normally, days that are omitted, whether by a global OMIT command or the local OMIT or OMITFUNC keywords in a REM statement, only affect the counting of the -back or the +delta. For example, suppose you have a meeting every Wednesday. Suppose, too, that you have indicated 11 Nov as a holiday:

	OMIT 11 Nov +4 MSG Remembrance Day
	REM Wed +1 MSG Code meeting %b.

The above sequence will issue a reminder about a meeting for 11 November 1992, which is a Wednesday. This is probably incorrect. There are three options:

BEFORE
    This keyword moves the reminder to before any omitted days. Thus, in the above example, use of BEFORE would cause the meeting reminder to be triggered on Tuesday, 10 November 1992.

AFTER
    This keyword moves the reminder to after any omitted days. In the above example, the meeting reminder would be triggered on Thursday, 12 November 1992.

SKIP
    This keyword causes the reminder to be skipped completely on any omitted days. Thus, in the above example, the reminder would not be triggered on 11 November 1992. However, it would be triggered as usual on the following Wednesday, 18 November 1992.

The BEFORE and AFTER keywords move the trigger date of a reminder to before or after a block of omitted days, respectively. Suppose you normally run a backup on the first day of the month. However, if the first day of the month is a weekend or holiday, you run the backup on the first working day following the weekend or holiday. You could use:

	REM 1 OMIT Sat Sun AFTER RUN do_backup

Let's examine how the trigger date is computed. The 1 specifies the first day of the month. The local OMIT keyword causes the AFTER keyword to move the reminder forward past weekends. Finally, the AFTER keyword will keep moving the reminder forward until it has passed any holidays specified with global OMIT commands.

TIMEZONE SUPPORT

The REM command supports an optional TZ keyword, which should be followed by the case-sensitive time zone name in which the command is to be interpreted. Note that if you use the TZ keyword, then you must also use an AT clause. Here are some examples:

    REM Wednesday AT 14:00 TZ America/Toronto MSG 2PM Eastern (%2).
    REM Wednesday AT 23:59 TZ America/Los_Angeles SATISFY [$Td == 13] MSG Foo %b %2.

Within a SATISFY clause and an OMITFUNC function, all trigger functions and the trigger date are interpreted in the time zone specified in the REM command. Outside the REM command, however, trigger functions are adjusted to the local time zone. If the local time zone is UTC and we feed Remind the following file on 2025-09-04 UTC:

    SET $AddBlankLines 0
    BANNER %
    REM Wednesday AT 14:00 TZ America/Toronto MSG 2PM Eastern (%2).
    set a $T
    set b $Tt
    REM MSG a = [a], b = [b]
    REM Wednesday AT 23:59 TZ America/Los_Angeles SATISFY [$Td == 13] MSG Foo %b %2.
    set c $T
    set d $Tt
    REM MSG c = [c], d = [d]

Then the output is as follows:

    a = 2025-09-10, b = 18:00
    c = 2026-05-14, d = 06:59

That is because the trigger date of the first (Wednesday, 2025-09-10 at 14:00 Eastern time) is 2025-09-10 at 18:00 UTC. In the second case, Wednesday, 13 May 2026 is the SATISFied trigger date, which is adjusted to Thursday, 14 May 2026 at 06:59 UTC because of the time zone adjustment.

If you use an invalid time zone name after the TZ keyword, results are undefined. As mentioned previously, time zone names are case-sensitive; America/Toronto is valid, but america/toronto is not.

If you are on a system that stores time zone data in /usr/share/zoneinfo, then Remind will attempt to validate the time zone name and will warn you if it appears to be invalid. If you want to specify a time zone that lacks a file under /usr/share/zoneinfo anyway, and want to suppress the warning, prefix the time zone name with "!". For example:

    REM Thursday AT 14:45 TZ !EST+5EDT,M3.2.0/2,M11.1.0/2 MSG Old TZ format

In a reminder with the TZ keyword, OMIT dates are evaluated in the specified time zone. Here's an example: Suppose the local time zone is America/Toronto and you have this script:

    # A Friday
    OMIT 2025-09-05
    # A Saturday
    OMIT 2025-09-13
    REM Saturday AT 01:00 TZ Europe/Amsterdam SKIP MSG Early Sat AM

On 2025-09-05 in the America/Toronto time zone, the reminder will trigger. Even though 2025-09-05 has been OMITted, the SKIP keyword evaluates the date in the Europe/Amsterdam time zone, and 2025-09-06 (the trigger date) is not omitted.

Conversely, on 2025-09-12 in the America/Toronto time zone, the reminder will not trigger. Even though 2025-09-12 is not OMITted, 2025-09-13 is, and that is the trigger date in the Europe/Amsterdam time zone.

THE DO, INCLUDE AND SYSINCLUDE COMMANDS

Remind allows you to include other files in your reminder script, similar to the C preprocessor #include directive. For example, you might organize different reminders into different files like this:

        INCLUDE holidays.rem
        INCLUDE birthdays.rem
        INCLUDE "quote files with spaces.rem"

INCLUDE files can be nested up to a depth of 8. As shown above, if a filename has spaces in it (not recommended!) you can use double-quotes around the filename.

If you specify a filename of "-" in the INCLUDE command, Remind will begin reading from standard input.

If you specify a directory as the argument to INCLUDE, then Remind will process all files (but not subdirectories!) in that directory that match the shell pattern "*.rem". The files are processed in sorted order; the sort order matches that used by the shell when it expands "*.rem".

Note that the file specified by an INCLUDE command is interpreted relative to the current working directory of the Remind process. If you want to include a file relative to the directory containing the currently-processing file, use DO instead. For example, if the current file is /home/user/.reminders/foo.rem and Remind's working directory is /home/user, then:

    # Read /home/user/.reminders/bar.rem
    DO bar.rem
    # Read /usr/share/bar.rem - absolute path
    DO /usr/share/bar.rem
    # Read /home/user/bar.rem
    INCLUDE bar.rem
    # Read /usr/share/bar.rem - absolute path
    INCLUDE /usr/share/bar.rem

Arguably, the INCLUDE command should have worked the way DO does right from the start, but changing it would have broken backward-compatibility, hence the introduction of DO.

Note that if the currently-processing reminders file was specified as a symbolic link to a file that is not in the same directory as the symbolic link itself, DO will fail. Remind does not resolve the real path of symbolic links, so you should avoid using symbolic links to files.

The SYSINCLUDE command is similar to DO, but it looks for relative pathnames under the system directory containing standard reminder scripts. For this installation of Remind, the system directory is "/usr/local/share/remind".

THE RETURN COMMAND

The RETURN command causes Remind to ignore the remaining contents of the file currently being processed. It can be used as a quick way to "exit" from an included file (though it also works at the top-level.)

Here is an example of how RETURN might be used:

        IF already_done
            RETURN
        ENDIF
        set already_done 1
        preserve already_done
        # Do expensive processing here

THE RUN COMMAND

If you include other files in your reminder script, you may not always entirely trust the contents of the other files. For example, they may contain RUN-type reminders that could be used to access your files or perform undesired actions. The RUN command can restrict this: If you include the command RUN OFF in your top-level reminder script, any reminder or expression that would normally execute a system command is disabled. RUN ON will re-enable the execution of system commands. Note that the RUN ON command can only be used in your top-level reminder script; it will not work in any files accessed by the INCLUDE command. This is to protect you from someone placing a RUN ON command in an included file. However, the RUN OFF command can be used at top level or in an included file.

If you run Remind with the -r command-line option, RUN-type reminders and the shell() function will be disabled, regardless of any RUN commands in the reminder script. However, any command supplied with the -k option will still be executed.

In addition, Remind contains a few other security features. It will not read a file that is group- or world-writable. It will not run set-uid. If it reads a file you don't own, it will disable RUN and the shell() function. And if it is run as root, it will only read files owned by root.

Note that if Remind reads standard input, it does not attempt to check the ownership of standard input, even if it is coming from a file, and hence does not disable RUN and shell() in this situation.

THE EXPR COMMAND

Remind lets you completely disable expression evaluation. This could be useful if you are running Remind on a somewhat-untrustworthy file that is not expected to contain expressions. To disable expression evaluation, use:

        EXPR OFF

If Remind encounters an expression while EXPR OFF is in effect, it returns an error

To re-enable expression evaluation, use:

        EXPR ON

As with RUN ON, EXPR ON can be used only in the top-level script, not in an included file.

THE INCLUDECMD COMMAND

Remind allows you to execute a shell command and evaluate the output of that command as if it were an included file. For example, you could have scripts that extract reminders out of a database and print them on stdout as REM commands. Here is an example:

	INCLUDECMD extract_reminders_for dfs

We assume that the command "extract_reminders_for" extracts reminders out of a central database for the named user. Another use-case of INCLUDECMD is if you have your reminders stored in a file in some non-Remind format; you can write a command that transforms them to Remind format and then Remind can "include" the file with an appropriate INCLUDECMD command.

Note that if RUN is disabled, then INCLUDECMD will fail with the error message "RUN disabled"

Remind arranges so that when the command specified by INCLUDECMD is executed, its standard input is opened to /dev/null.

INCLUDECMD passes the rest of the line to popen(3), meaning that the command is executed by the shell. As such, shell meta-characters may need escaping or arguments quoting, depending on what you're trying to do. Remind itself does not perform any modification of the command line (apart from the normal [expr] expression-pasting mechanism).

If the command passed to INCLUDECMD begins with an exclamation mark "!", then Remind disables RUN for the output of the command. If you are running a command whose output you don't quite trust, you should prefix it with "!" so that any RUN commands it emits fail.

An INCLUDECMD command counts towards the INCLUDE nesting depth. For any given Remind run, a given INCLUDECMD command is only executed once and the results are cached. For example, if you generate a calendar, each unique INCLUDECMD command is run just once, not once for each day of the produced calendar. "Uniqueness" is determined by looking at the command that will be passed to the shell, so if (for example) your INCLUDECMD uses expression-pasting that results in differences depending on the value of today(), then each unique version of the command will be executed once.

If a given reminder file contains more than one identical INCLUDECMD, only the first one will actually be executed. All subsequent identical ones will use the cached output from the first one.

THE BANNER COMMAND

When Remind first issues a reminder, it prints a message like this:

	Reminders for Friday, 30th October, 1992 (today):

(The banner is not printed if any of the calendar-producing options is used, or if the -k option is used.)

The BANNER command lets you change the format. It should appear before any REM commands. The format is:

    BANNER format

The format is similar to the body of a REM command. It is passed through the substitution filter, with an implicit trigger of the current system date. Thus, the default banner is equivalent to:

	BANNER Reminders for %w, %d%s %m, %y%o:

You can disable the banner completely with BANNER %. Or you can create a custom banner:

	BANNER Hi - here are your reminders for %y-%t-%r:

CONTROLLING THE OMIT CONTEXT

Sometimes, it is necessary to temporarily change the global OMITs that are in force for a few reminders. Three commands allow you to do this:

PUSH-OMIT-CONTEXT
    This command saves the current global OMITs on an internal stack.

CLEAR-OMIT-CONTEXT
    This command clears all of the global OMITs, starting you off with a "clean slate."

POP-OMIT-CONTEXT
    This command restores the global OMITs that were saved by the most recent PUSH-OMIT-CONTEXT.

For example, suppose you have a block of reminders that require a clear OMIT context, and that they also introduce unwanted global OMITs that could interfere with later reminders. You could use the following fragment:

	PUSH-OMIT-CONTEXT	# Save the current context
	CLEAR-OMIT-CONTEXT	# Clean the slate
	# Block of reminders goes here
	POP-OMIT-CONTEXT	# Restore the saved omit context

EXPRESSIONS

In certain contexts, to be described later, Remind will accept expressions for evaluation. Remind expressions resemble C expressions, but operate on different types of objects.

DATA TYPES

Remind expressions operate on five types of objects:

INT The INT data type consists of the integers representable in one machine word. The INT data type corresponds to the C "int" type.

STRING
    The STRING data type consists of strings of characters. It is somewhat comparable to a C character array, but more closely resembles the string type in BASIC.

    Remind normally expects to be running in a UTF-8 environment. In this environment, there is a difference between bytes and characters since in UTF-8, a character may be represented by a sequence of more than one byte. For example, in a UTF-8 environment, the string "🙂" contains one character but four bytes. And the string "één" contains three characters but five bytes.

    Remind has a set of functions that work on bytes, namely index, strlen and substr, and several more. These are not safe to use on multi-byte strings; instead use mbindex, mbstrlen and mbsubstr, and the mb variants of the others. If you know for sure that a string contains only single-byte characters, then the byte-oriented versions may be used and are faster than the multi-byte versions.

TIME
    The TIME data type is used for two different purposes: To represent a time of day with one-minute precision or to represent a duration with one-minute precision. The context of where a TIME is used determines whether it is interpreted as a time of day or a duration.

    In contexts where a TIME represents a time of day, it may range from 00:00 to 23:59 and is stored internally as an integer from 0 to 1439 representing the number of minutes since midnight.

    In contexts where a TIME represents a duration, there is no upper limit on the hour component (beyond that imposed by the restriction that a duration expressed in minutes must fit into the signed integer type of your CPU architecture.) Internally, a duration is stored as an integer number of minutes.

DATE
    The DATE data type consists of dates (later than 1 January 1990.) Internally, DATE objects are stored as the number of days since 1 January 1990.

DATETIME
    The DATETIME data type consists of a date and time together. Internally, DATETIME objects are stored as the number of minutes since midnight, 1 January 1990. You can think of a DATETIME object as being the combination of DATE and TIME parts.

CONSTANTS

The following examples illustrate constants in Remind expressions:

INT constants
    12, 36, -10, 0, 1209, 0x1F, 0xfe00 (the last two demonstrate the use of hexadecimal constants)

STRING constants
    "Hello there", "This is a test", "\nHello\tThere", "", "π is Cool! 🙂"

    Note that the empty string is represented by "". Remind supports the escape sequences "\a", "\b", "\f", "\n", "\r", "\t" and "\v" which have the same meanings as their counterparts in C. It also supports "\xAB" where A and B are hexadecimal digits; this operates just as in C. The "\x" must be followed by one or two hex digits; the escape sequence "\x00" is not permitted.

    To include a quote in a string, use "\"". Any other character preceded by a backslash is inserted into the string as-is, but the backslash itself is removed. To include a backslash in a string, use "\\".

TIME constants
    12:33, 0:01, 14:15, 16:42, 12.16, 13.00, 1.11, 4:30PM, 12:20am

    Note that TIME constants may be written in 24-hour format or in common "AM/PM" format. If you use "AM/PM" format, then the hour can range from 1 to 12. Either a period or colon can be used to separate the minutes from the hours. However, Remind will consistently output times in 24-hour format using only one separator character. (The output separator character is chosen at compile-time.)

    If the TIME is used where Remind expects a time-of-day (for example, in an AT clause), then it can be written in 24-hour format (ranging from 00:00 to 23:59) or 12-hour format (ranging from 12:00am to 11:59pm). If the TIME is used where Remind expects a duration, it must not have an am or pm suffix and the hour can be as large as you want, so long as the total number of minutes in the duration fits in a signed integer variable.

    For convenience, a TIME constant may be surrounded by single quotes to match DATE and DATETIME constants, but these quotes are optional. That is, 12:56 and '12:56' represent the same TIME constant.

DATE constants
    DATE constants are expressed as 'yyyy/mm/dd' or 'yyyy-mm-dd', and the single quotes must be supplied. This distinguishes date constants from division or subtraction of integers. Examples:

    '1993/02/22', '1992-12-25', '1999/01/01'

    Note that DATE values are printed without the quotes. Although either '-' or '/' is accepted as a date separator on input, when dates are printed, only one will be used. The choice of whether to use '-' or '/' is made at compile-time. Note also that versions of Remind prior to 03.00.01 did not support date constants. In those versions, you must create dates using the date() function. Also, versions prior to 03.00.02 did not support the '-' date separator.

DATETIME constants
    DATETIME constants are expressed similarly to DATE constants with the addition of an "@HH:MM" part, optionally followed by "am" or "pm". For example:

    '2008-04-05@23:11', '1999/02/03@14:06', '2001-04-07@08:30', '2020-01-01@3:20pm'

    DATETIME values are printed without the quotes. Notes about date and time separator characters for DATE and TIME constants apply also to DATETIME constants.

ZERO VALUES AND TRUE/FALSE

All types have an associated zero value, which is treated as false by the IF command, the IIF function, and the logical operators. The zero values are:

    INT - 0

    DATE - '1990-01-01'

    TIME - 00:00

    DATETIME - '1990-01-01@00:00'

    STRING - "" (the empty string)

Any value other than the zero value is treated as true.

OPERATORS

Remind has the following operators. Operators on the same line have equal precedence, while operators on lower lines have lower precedence than those on higher lines. The operators approximately correspond to C operators.

	!  -            (unary logical negation and arithmetic negation)
	*  /  %         (multiplication, division, modulus)
	+  -            (addition/concatenation, subtraction)
	<  <=  >  >=    (comparisons)
	==  !=          (equality and inequality tests)
	&&              (logical AND)
	||              (logical OR)

DESCRIPTION OF OPERATORS

!   Logical negation. Can be applied to any type. If the operand is non-zero, returns 0. Otherwise, returns 1.

-   Unary minus. Can be applied to an INT. Returns the negative of the operand.

*   Multiplication. Returns the product of two INTs. Alternatively, if one argument is a STRING and the other an INT, returns a STRING consisting of the INT number of repeats of the original STRING. In this case, the INT argument cannot be negative.

/   Integer division. Returns the quotient of two INTs, discarding the remainder.

%   Modulus. Returns the remainder upon dividing one INT by another.

+   Has several uses. These are:

    INT + INT - returns the sum of two INTs.

    INT + TIME or TIME + INT - returns a TIME obtained by adding INT minutes to the original TIME. The result will always range from 00:00 through 23:59.

    TIME + TIME treats the second TIME parameter as a duration, converting it to an integer number of minutes past midnight, and then performs addition as with TIME + INT.

    INT + DATE or DATE + INT - returns a DATE obtained by adding INT days to the original DATE.

    INT + DATETIME or DATETIME + INT - returns a DATETIME obtained by adding INT minutes to the original DATETIME.

    DATETIME + TIME or TIME + DATETIME treats the TIME parameter as a duration, converting it to an integer number of minutes past midnight, and then performs addition as with DATETIME + INT.

    STRING + STRING - returns a STRING that is the concatenation of the two original STRINGs.

    STRING + anything or anything + STRING - converts the non-STRING argument to a STRING, and then performs concatenation. See the coerce() function.

-   Has several uses. These are:

    INT - INT - returns the difference of two INTs.

    DATE - DATE - returns (as an INT) the difference in days between two DATEs.

    TIME - TIME - returns (as an INT) the difference in minutes between two TIMEs.

    DATETIME - DATETIME - returns (as an INT) the difference in minutes between two DATETIMEs.

    DATE - INT - returns a DATE that is INT days earlier than the original DATE.

    TIME - INT - returns a TIME that is INT minutes earlier than the original TIME.

    DATETIME - INT - returns a DATETIME that is INT minutes earlier than the original DATETIME.

    DATETIME - TIME - coerces the TIME to an INT and then performs subtraction as above.

<, <=, >, and >=
    These are the comparison operators. They can take operands of any type, but both operands must be of the same type. The comparison operators return 1 if the comparison is true, or 0 if it is false. Note that string comparison is done following the lexical ordering of characters on your system, and that upper and lower case are distinct for these operators.

==, !=
    == tests for equality, returning 1 if its operands are equal, and 0 if they are not. != tests for inequality.

    If the operands are not of the same type, == returns 0 and != returns 1. Again, string comparisons are case-sensitive.

&&  This is the logical AND operator. Returns the second operand if both operands are non-zero. Otherwise, returns whichever operand is zero. Operands can be any type and "zero" is interpreted as appropriate for each operand's type.

||  This is the logical OR operator. It returns the first operand that is non-zero; if both operands are zero, then returns the second operand. Operands can be any type and "zero" is interpreted as appropriate for each operand's type.

NOTES

If the result of an addition, subtraction or multiplication operation would not fit in a C "int" type, Remind issues a "Number too high" error. Unlike C, integer operations will not simply give the wrong answer in case of overflow.

Operators of equal precedence are always evaluated from left to right, except where parentheses dictate otherwise. This is important, because the enhanced "+" operator is not necessarily associative. For example:

	1 + 2 + "string" + 3 + 4  yields "3string34"
	1 + (2 + "string") + (3 + 4)  yields "12string7"
	12:59 + 1 + "test"  yields "13:00test"
	12:59 + (1 + "test")  yields "12:591test"

The logical operators are so-called short-circuit operators, as they are in C. This means that if the first operand of || is true, then the second operand is not evaluated. Similarly, if the first operand of && is false, then the second operand is not evaluated.

VARIABLES

Remind allows you to assign values to variables. The SET command is used as follows:

SET var expr

Var is the name of a variable. It must start with a letter or underscore, and consist only of letters, digits and underscores. Only the first 64 characters of a variable name are significant. Variable names are not case sensitive; thus, "Afoo" and "afOo" are the same variable. Examples:

	SET a 10 + (9*8)
	SET b "This is a test"
	SET mydir getenv("HOME")
	SET time 12:15
	SET date today()

Note that variables themselves have no type. They take on the type of whatever you store in them.

Variables set with SET or on the command-line with -ivar=expr have global scope.

To delete a variable, use the UNSET command:

UNSET var [var...]

For example, to delete all the variables declared above, use:

	UNSET a b mydir time date

SYSTEM VARIABLES

In addition to the regular user variables, Remind has several "system variables" that are used to query or control the operating state of Remind. System variables are available starting from version 03.00.07 of Remind.

All system variables begin with a dollar sign '$'. They can be used in SET commands and expressions just as regular variables can. All system variables always hold values of a specified type. In addition, some system variables cannot be modified, and you cannot create new system variables. System variables can be initialized on the command line with the -i option, but you may need to quote them to avoid having the shell interpret the dollar sign. System variable names are not case-sensitive.

The following system variables are defined. Those marked "read-only" cannot be changed with the SET command. All system variables hold values of type INT, unless otherwise specified.

$AddBlankLines
    If set to 1 (the default), then Remind normally prints a blank line after the banner and each reminder. (This can be suppressed by ending the reminder or banner with a single percent sign.) If $AddBlankLines is set to 0, then Remind does not print the blank line. In this case, ending a reminder with % has no effect. If you do want a blank line after a reminder, end it with %_ to insert a newline.

$CalcUTC
    If 1 (the default), then Remind uses C library functions to calculate the number of minutes between local and Universal Time Coordinated. This affects astronomical calculations (sunrise() for example.) If 0, then you must supply the number of minutes between local and Universal Time Coordinated in the $MinsFromUTC system variable.

$CalMode (read-only)
    If non-zero, then the -c option was supplied on the command line.

$CalType (read-only, STRING type)
    If the -c, -s or -p command-line options were used, then this variable has the value "monthly". If -c+, -s+ or -p+ were used, then "weekly". Otherwise, "none".

$Daemon (read-only)
    If "daemon mode" -z was invoked, contains the number of minutes between wakeups. If not running in daemon mode, contains 0. In server mode (either -z0 or -zj), contains -1.

$DateSep (STRING type)
    This variable can be set only to "/" or "-". It holds the character used to separate portions of a date when Remind prints a DATE or DATETIME value.

$DedupeReminders
    If this variable is set to 1, then Remind will suppress duplicate reminders. A given reminder is considered to be a duplicate of a previous one if it has the exact same trigger date, trigger time, and body. By default, this variable is set to 0 and Remind does not suppress duplicate reminders.

    As an example, consider the following reminder file:

            SET $DedupeReminders 1
            REM Wednesday MSG Phooey
            REM 20 MSG Phooey

    On Wednesday, 20 November 2024, only one "Phooey" will be issued. In December of 2024, "Phooey" will be issued every Wednesday as well as on Friday, 20 December 2024

    If you set $DedupeReminders to 0, then Remind does not even track reminders to detect duplicates. Consider the following example:

            SET $DedupeReminders 0
            REM Wednesday MSG Hello
            SET $DedupeReminders 1
            REM Wednesday MSG Hello

    Every Wednesday, Remind will issue two "Hello" reminders. Because $DedupeReminders was 0 when the first "Hello" was issued, it won't be tracked for potential duplicates.

    Duplicates are detected after all variable expansion and substitutions have been done. Consider the following:

            SET $DedupeReminders 1
            set a "foo"
            REM MSG [a]
            set a "bar"
            REM MSG [a]
            set a "foo"
            REM MSG [a]

    The first REM will trigger and print "foo". The second will trigger and print "bar". The third will not trigger because it's a duplicate of the first "foo".

$DefaultColor (STRING type)
    This variable can be set to a string that has the form of three space-separated numbers. Each number must be an integer from 0 to 255, or all three numbers must be -1. The default value of $DefaultColor is "-1 -1 -1", which suppresses default coloring of MSG-type reminders. If you set $DefaultColor to any other value, then all MSG-, MSF- and CAL-type reminders are effectively converted into SPECIAL COLOR reminders whose color value is specified by $DefaultColor.

    Unlike other system variables, the value of $DefaultColor is not preserved between calendar iterations; rather, it is reset to "-1 -1 -1" at the start of each iteration.

$DefaultPrio
    The default priority assigned to reminders without a PRIORITY clause. You can set this as required to adjust the priorities of blocks of reminders without having to type priorities for individual reminders. At startup, $DefaultPrio is set to 5000; it can range from 0 to 9999.

$DefaultDelta
    You can set this variable to a number from 0 through 10000. If set to a non-zero number, then Remind triggers any REM statement that lacks a delta as if it had a delta of ++$DefaultDelta. By default, $DefaultDelta is zero.

$DefaultTDelta
    The default time delta used if no +N is given in an AT clause. This is normally 0, but can be set with the -tt option or explicitly set in your script. If $DefaultDelta is non-zero, you can use an explicit delta of +0 in an AT clause to countermand the default delta.

$DeltaOverride (read-only)
    If non-zero, corresponds to the n argument given to a -tn command-line option.

$DontFork (read-only)
    If non-zero, then the -c option was supplied on the command line.

$DontTrigAts (read-only)
    The number of times that the -a option was supplied on the command line.

$DontQueue (read-only)
    If non-zero, then the -q option was supplied on the command line.

$EndSent (STRING type)
    Contains a list of characters that end a sentence. The MSF keyword inserts two spaces after these characters. Initially, $EndSent is set to ".!?" (period, exclamation mark, and question mark.)

$EndSentIg (STRING type)
    Contains a list of characters that should be ignored when MSF decides whether or not to place two spaces after a sentence. Initially, is set to "'>)]}"+CHAR(34) (single-quote, greater-than, right parenthesis, right bracket, right brace, and double-quote.)

    For example, the default values work as follows:

    	MSF He said, "Huh! (Two spaces will follow this.)"  Yup.

    because the final parenthesis and quote are ignored (for the purposes of spacing) when they follow a period.

$ExpressionTimeLimit
    If set to a non-zero value n, than any expression that takes longer than n seconds to evaluate will be aborted and an error returned. This is to prevent maliciously-crafted expressions for creating a denial-of-service. In an included file, $ExpressionTimeLimit can only be lowered from its current value. In the top-level file, it can be set to any value, including zero to disable the time limit.

$FirstIndent
    The number of spaces by which to indent the first line of a MSF-type reminder. The default is 0.

$FoldYear
    The standard Unix library functions may have difficulty dealing with dates later than 2037. If this variable is set to 1, then the UTC calculations "fold back" years later than 2037 before using the Unix library functions. For example, to find out whether or not daylight saving time is in effect in June, 2077, the year is "folded back" to 2027, because both years begin on a Friday, and both are non-leapyears. The rules for daylight saving time are thus presumed to be identical for both years, and the Unix library functions can handle 2027. By default, this variable is 0. Set it to 1 if the sun or UTC functions misbehave for years greater than 2037. See also the section "MACHINES WITH A 32-BIT TIME_T TYPE"

$FormWidth
    The maximum width of each line of text for formatting MSF-type reminders. The default is the width of the terminal in columns, minus 8, but clamped at a minimum of 20 and a maximum of 500. If standard output is not a terminal, then the default is 72.If an MSF-type reminder contains a word too long to fit in this width, it will not be truncated - the width limit will be ignored.

$HideCompletedTodos (read-only)
    If non-zero, then the --hide-completed-todos option was supplied on the command line.

$HushMode (read-only)
    If non-zero, then the -h option was supplied on the command line.

$IgnoreOnce (read-only)
    If non-zero, then the -o option was supplied on the command line, or implicitly enabled for some other reason. In this case, ONCE directives will be ignored.

$InfDelta (read-only)
    If non-zero, then the -t option was supplied on the command line, with no n argument.

$IntMax (read-only)
    The largest representable INT. On a machine with 32-bit signed integers using twos-complement representation, this will be 2147483647.

$IntMin (read-only)
    The smallest representable INT. On a machine with 32-bit signed integers using twos-complement representation, this will be -2147483648.

$Latitude (STRING type)
    The latitude of your location, expressed as a string that is a floating-point number. Because Remind does not have a native floating-point type, we need to express it as a string. $Latitude can range from "-90.0" to "90.0", with positive numbers representing points north of the equator and negative numbers representing south. Note that regardless of your locale, $Latitude is always interpreted in the "C" locale and as such, the decimal point must be a period (".").

$Longitude (STRING type)
    The longitude of your location, expressed as a string that is a floating-point number. Because Remind does not have a native floating-point type, we need to express it as a string. $Longitude can range from "-180.0" to "180.0", with positive numbers representing points east of the Greenwich Meridian and negative numbers representing west. Note that regardless of your locale, $Longitude is always interpreted in the "C" locale and as such, the decimal point must be a period (".").

    For example, the coordinates of the Statue of Liberty in New York City are approximately set by:

        SET $Latitude   "40.68933"
        SET $Longitude "-74.04454"

$LatDeg, $LatMin, $LatSec (DEPRECATED)
    These specify the latitude of your location. $LatDeg can range from -90 to 90, and the others from -59 to 59. Northern latitudes are positive; southern ones are negative. For southern latitudes, all three components should be negative. These three variables are deprecated; you should use $Latitude instead.

$Location (STRING type)
    This is a string specifying the name of your location. It is usually the name of your town or city. It can be set to whatever you like, but good style indicates that it should be kept consistent with the latitude and longitude system variables.

$LongDeg, $LongMin, $LongSec (DEPRECATED)
    These specify the longitude of your location. $LongDeg can range from -180 to 180. Western longitudes are positive; eastern ones are negative. Note that all three components should have the same sign: All positive for western longitudes and all negative for eastern longitudes. Note that for historical reasons, the sign for longitude is different from the usual convention! If you find the longitude of your location from a search engine, you will most likely need to invert the sign to have it work correctly with Remind. These three variables are deprecated; you should use $Longitude instead. Note also that $Longitude uses the standard convention of negative for western longitudes and positive for eastern ones.

    The latitude and longitude information is required for the functions sunrise() and sunset(). Default values can be compiled into Remind, or you can SET the correct values at the start of your reminder scripts.

    Note that setting any of $LongDec, $LongMin and $LongSec updates $Longitude correspondingly, and setting $Longitude updates $LongDeg, $LongMin and $LongSec. Similar rules apply to $Latitude, $LatDeg, $LatMin and $LatSec.

$JSONMode (read-only)
    If non-zero, then the --json command-line option was supplied.

$MaxLateMinutes
    This variable controls how Remind reacts to a computer being suspended and then woken. Normally, if a timed reminder is queued and then the computer suspended, and then the computer is woken after the timed reminder's trigger time, Remind will trigger the timer anyway, despite the fact that the trigger time has already passed.

    If you set $MaxLateMinutes to a non-zero integer between 1 and 1440, then Remind will not trigger a timed reminder whose trigger time is more than $MaxLateMinutes minutes in the past.

    Note that Remind uses the value of $MaxLateMinutes that is in effect when it has finished reading the reminder file and puts itself in the background. Generally, you should set $MaxLateMinutes once near the beginning of the file and not change it after that.

$MaxSatIter
    The maximum number of iterations for the SATISFY clause (described later.) Must be at least 10. The default value is 10,000.

$MaxStringLen
    A limit on the longest string that Remind will allow you to create. The default is 65535. If you set $MaxStringLen to 0 or to -1, then remind will allow you to create arbitrarily-long strings, at least until it runs out of memory. We do not recommend setting $MaxStringLen to 0 or -1 because it is very easy to write code that DOSes Remind in that case.

$MinsFromUTC
    The number of minutes between Universal Time Coordinated and local time. If $CalcUTC is non-zero, this is calculated upon startup of Remind. Otherwise, you must set it explicitly. If $CalcUTC is zero, then $MinsFromUTC is used in the astronomical calculations. You must adjust it for daylight saving time yourself. Also, if you want to initialize $MinsFromUTC using the -i command-line option, you must also set $CalcUTC to 0 with the -i option.

$NextMode (read-only)
    If non-zero, then the -n option was supplied on the command line.

$MaxFullOmits (read-only)
    The maximum number of full OMITs allowed (a compiled-in constant.)

$MaxPartialOmits (read-only)
    The maximum number of partial OMITs allowed (a compiled-in constant.)

$NumFullOmits (read-only)
    The number of full OMITs in the current OMIT context.

$NumPartialOmits (read-only)
    The number of partial OMITs in the current OMIT context.

$NumQueued (read-only)
    Contains the number of reminders queued so far for background timed triggering.

$NumTrig (read-only)
    Contains the number of reminders triggered for the current date. One use for this variable is as follows: Suppose you wish to shade in the box of a PostScript calendar whenever a holiday is triggered. You could save the value of $NumTrig in a regular variable prior to executing a block of holiday reminders. If the value of $NumTrig after the holiday block is greater than the saved value, then at least one holiday was triggered, and you can execute the command to shade in the calendar box. (See the section "Calendar Mode".)

    Note that $NumTrig is affected only by REM commands; triggers in IFTRIG commands do not affect it.

$OnceFile (STRING type)
    If you set this variable to a non-empty string, then rather than using the file access date to determine whether or not to run a ONCE-type reminder, Remind will maintain a timestamp in the file $OnceFile. This is more reliable than using the access date of the reminder file.

    If $OnceFile does not exist, then it will be created the first time a ONCE keyword is processed. The file must be writable by the current user. If you try to set $OnceFile after a ONCE reminder has already been processed, Remind will issue a warning and ignore the attempt to set $OnceFile.

$ParseUntriggered
    A flag indicating whether or not Remind should fully parse REM statements that are not triggered. 0 (the default) means to skip parsing them and 1 means to parse them.

    For example, if we have the following REM statement:

                REM 2020-01-01 MSG ["bad_expression" / 2]

    Then if $ParseUntriggered is set to 1, Remind will fully parse the line and issue a "Type mismatch" error even if the reminder is not triggered. However, if $ParseUntriggered is set to 0, the default, then Remind will not issue the error except on 2020-01-01, when the reminder is triggered.

    Keeping $ParseUntriggered at 0 may slightly improve performance, at the risk of not catching errors until a reminder is triggered. We recommend leaving it set to 0.

$PrefixLineNo (read-only)
    If non-zero, then the -l option was supplied on the command line.

$PSCal (read-only)
    If non-zero, then the -p option was supplied on the command line.

$Repeat (read-only)
    If this variable holds a non-zero value n, then a command-line argument of *n was supplied to specify repeated runs of Remind..

$RunOff (read-only)
    If non-zero, the RUN directives are disabled.

$Shaded (read-only)
    Returns the number of times a SHADE special reminder has triggered. This variable is set only in calendar mode, not agenda mode. You can use this variable to avoid shading a calendar day that has already been shaded.

    For example, suppose you want to shade all calendar boxes yellow if any reminders have triggered on that day. But if a box has been explicitly shaded, you don't want to overwrite that shading. You could use something like this:

            SET n $NumTrig
            # Do all your reminders here...
            # If anything has triggered and the box is
            # not already shaded, then shade it yellow
            IF $NumTrig > n && !$Shaded
                REM SPECIAL SHADE 255 255 128
            ENDIF

$SimpleCal (read-only)
    Set to a non-zero value if either of the -p or -s command-line options was supplied.

$SortByDate (read-only)
    Set to 0 if no -g option is used, 1 if sorting by date in ascending order, or 2 if sorting by date in descending order.

$SortByPrio (read-only)
    Set to 0 if no -g option is used, 1 if sorting by priority in ascending order, or 2 if sorting by priority in descending order.

$SortByTime (read-only)
    Set to 0 if no -g option is used, 1 if sorting by time in ascending order, or 2 if sorting by time in descending order.

$SubsIndent
    The number of spaces by which all lines (except the first) of an MSF-type reminder should be indented. The default is 0.

$SuppressImplicitWarnings
    Normally, Remind issues a warning if a line begins with an unknown token and is treated as a REM command, or if a REM command is missing a type and is treated as a MSG-type reminder. Setting $SuppressImplicitWarnings to 1 suppresses these warnings. The default is 0 and we do not recommend disabling the warnings.

$SuppressLRM
    Normally, when Remind is run with the -c option in a UTF-8 locale, it emits a left-to-right mark sequence after printing day names or reminders. Some terminals render this incorrectly, so you can use:

        SET $SuppressLRM 1

    at the top of your reminder file to suppress the LRM sequences, or you can invoke Remind with the option '-i$SuppressLRM=1'.

$SysInclude (read-only, STRING type)
    A directory path containing standard reminder scripts. Currently, Remind ships with some standard holiday files and language packs. The value of $SysInclude is "/usr/local/share/remind" on this installation.

$T (read-only, DATE or INT type)
    Equivalent to trigdate(). (See BUILT-IN FUNCTIONS.)

$Tb (read-only, DATE or INT type)
    Equivalent to trigbase().

$Td (read-only)
    Equivalent to day(trigdate()).

$Tm (read-only)
    Equivalent to monnum(trigdate()).

$Tu (read-only, DATE or INT type)
    Equivalent to triguntil().

$Tw (read-only)
    Equivalent to wkdaynum(trigdate()).

$Ty (read-only)
    Equivalent to year(trigdate()).

$Tt (read-only, TIME or INT type)
    Equivalent to trigtime().

$TimeSep (STRING type)
    This variable can be set only to ":" or ".". It holds the character used to separate portions of a time when Remind prints a TIME or DATETIME value.

$TimetIs64bit (read-only)
    This variable returns 1 if the internal C time_t type is at least 64 bits long. If it returns 0, then the internal C library is unable to represent dates after about 2038, and Remind will use a workaround to avoid problems. See also the section "MACHINES WITH A 32-BIT TIME_T TYPE"

$TodoFilter (read-only)
    If 0, then both events and TODOs are being output. If 1, then the --only-todos command-line option was supplied. If 2, then the --only-events command-line option was supplied.

$UntimedFirst (read-only)
    Set to 1 if the -g option is used with a fourth sort character of "d"; set to 0 otherwise.

$U (read-only, DATE type)
    Exactly equivalent to today(). (See BUILT-IN FUNCTIONS.)

$Ud (read-only)
    Equivalent to day(today()).

$Um (read-only)
    Equivalent to monnum(today()).

$Uw (read-only)
    Equivalent to wkdaynum(today()).

$Uy (read-only)
    Equivalent to year(today()).

$UseVTColors (read-only)
    Set to 1 if the -@ or -cc options were used; 0 otherwise.

$UseBGVTColors (read-only)
    Set to 1 if the -@,,1 option was used; 0 otherwise.

$Use256Colors (read-only)
    Set to 1 if the -@1 option was used; 0 otherwise.

$UseTrueColors (read-only)
    Set to 1 if the -@2 option was used; 0 otherwise.

$TerminalBackground (read-only)
    Returns -1 if the terminal background color could not be determined, 0 if it was found to be dark (or was specified as dark with the -@,0 option) or 1 if it was found to be light (or specified as light with the -@,1 option.) The terminal background is considered to be "dark" if the average of the red, green and blue components is at most 85 out of 255, and if the maximum of any component is at most 128 out of 255.

$TerminalHyperlinks (INT type)
    If your terminal supports escape sequences to allow HTML-like anchors around text (see https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda), then you can set this variable to 1. Remind will then make any reminder with a "Url:" info string into a hyperlink in your terminal. By default, $TerminalHyperlinks is set to 1 if Remind's standard output is a terminal, or to 0 if it is not.

$WarningLevel (STRING type)
    As new versions of Remind are released, new warnings may be added. If your formerly-fine scripts suddenly start issuing warnings when you upgrade Remind, then as a stopgap measure, you may set $WarningLevel to a string of the form AB.CD.EF where AB, CD and EF are pairs of decimal digits. This will suppress any warnings that were introduced after Remind version AB.CD.EF. If you do not set $WarningLevel, then it defaults to the current version of Remind, meaning all warnings will be issued.

    For example, if you want the warnings you receive limited to what Remind 05.00.00 would have produced, use:

        SET $WarningLevel "05.00.00"

    We do not recommend setting $WarningLevel as a matter of course; you should use it to suppress warnings only for as long as it takes for you to fix your remind scripts so they no longer cause warnings to be emitted.

Note: If any of the calendar modes are in effect, then the values of $Daemon, $DontFork, $DontTrigAts, $DontQueue, $HushMode, $IgnoreOnce, $InfDelta, and $NextMode are not meaningful.

SAVING AND RESTORING VARIABLES

Just as with the OMIT context, you can save and restore the values of global variables and all (modifiable) system variables. For example:

        SET a 1
        UNSET b
        # Save variables
        PUSH-VARS $DefaultColor $AddBlankLines a b
        SET $DefaultColor "255 0 0"
        SET $AddBlankLines 0
        SET a 3
        SET b 4
        REM MSG Hello
        # Restore all the variables we pushed earlier
        POP-VARS
        # Now the changes to $DefaultColor and $AddBlankLines
        # have been undone.  Additionally, a is restored to 1
        # and b is unset

As you see from the example, PUSH-VARS takes a list of global variable names and/or system variable names. You can save the values of any modifiable system variables and any global variable. You can even push global variables that are not set.

The POP-VARS command restores the values of all system variables and global variables that were pushed by the most recent PUSH-VARS command. If you push an undefined global variable, then that variable is unset by the POP-VARS command.

BUILT-IN FUNCTIONS

Remind has a plethora of built-in functions. The syntax for a function call is the same as in C - the function name, followed a comma-separated list of arguments in parentheses. Function names are not case-sensitive. If a function takes no arguments, it must be followed by "()" in the function call. Otherwise, Remind will interpret it as a variable name, and probably not work correctly.

In the descriptions below, short forms are used to denote acceptable types for the arguments. The characters "i", "s", "d", "t" and "q" denote INT, STRING, DATE, TIME and DATETIME arguments, respectively. If an argument can be one of several types, the characters are concatenated. For example, "di_arg" denotes an argument that can be a DATE or an INT. "x_arg" denotes an argument that can be of any type. The type of the argument is followed by an underscore and an identifier naming the argument.

The built-in functions are:

_(s_message)
    Returns the translation table entry for message. If there is no such translation table entry, then returns message unmodified. For example, consider this sequence:

            TRANSLATE "Goodbye" "Tot ziens"
            SET a _("Goodbye")

    After those two lines have been executed, the variable a will be set to "Tot ziens". See the section THE TRANSLATION TABLE for more information.

    In the body of a reminder, the substitution sequence %(text) is (almost) the equivalent of [_("text")]. Therefore, the following reminders are almost equivalent:

            REM MSG %(Goodbye)
            REM MSG [_("Goodbye")]

    The only difference is that if _("Goodbye") contains a % sign, then that result will be run through the substitution filter, whereas in the first reminder, it will not. That is because the second REM command performs expression pasting followed by a substitution filter pass, while the first one performs the translation as part of the substitution filter (and does not make a second substitution filter pass.)

abs(i_num)
    Returns the absolute value of num.

access(s_file, si_mode)
    Tests the access permissions for the file file. Mode can be a string, containing a mix of the characters "rwx" for read, write and execute permission testing. Alternatively, mode can be a number as described in the UNIX access(2) system call. The function returns 0 if the file can be accessed with the specified mode, and -1 otherwise.

adawn([dq_date])
    Returns the time of "astronomical dawn" on the specified date. If date is omitted, defaults to today(). If a datetime object is supplied, only the date component is used.

adusk([dq_date])
    Returns the time of "astronomical twilight" on the specified date. If date is omitted, defaults to today().

ampm(tq_time [,s_am [,s_pm [,i_lz]]])
    Returns a STRING that is the result of converting time (which is either a TIME or a DATETIME object) to "AM/PM" format. The optional arguments am and pm are the strings to append in the AM and PM case, respectively; they default to "AM" and "PM". The optional argument lz specifies whether or not the hour should be padded to two digits with a leading zero. If lz is zero, then a leading 0 is not added; otherwise, the hour is padded out to two digits with a leading zero. If not supplied, lz defaults to zero.

    The function obeys the system variables $DateSep, $TimeSep and $DateTimeSep when formatting its output. Here are some examples of its output:

            ampm(0:22)                 returns "12:22AM"
            ampm(17:45, "am", "pm")    returns "5:45pm"
            ampm(17:45, "am", "pm", 1) returns "05:45pm"
            ampm('2020-03-14@21:34')   returns "2020-03-14@9:34PM"

ansicolor(i_red, i_green, i_blue [,i_bg [,i_clamp]])
    Returns a STRING that contains an ANSI escape sequence for changing the terminal text color. The parameters red, green and blue are integers from 0 to 255 specifying the value of the respective color component. As a special case, all three values can be -1, in which case the ANSI sequence "ESC[0m" is returned, which resets all text attributes to normal.

    The string returned by ansicolor depends on the color mode that Remind is running in, as specified by the -@ option. If color mode is not enabled, then ansicolor always returns the empty string. Otherwise, it returns the escape sequence that best approximates the color according to the -@ color mode.

    The optional bg argument is either 0 or 1. If 0 (the default), then the foreground color is set. If 1, then the background color is set. Note that setting the background color only works in 256-color or true-color mode.

    The optional clamp argument is either 0 or 1. If 0 (the default), then colors are not adjusted based on the terminal background color. If 1, then Remind attempts to adjust dark or bright colors so they have enough contrast to be visible in the terminal.

    The first three arguments may alternatively be specified as a string consisting of three space-separated numbers, as in this example: "128 128 0"

    As a special case, ansicolor("") is equivalent to ansicolor(-1,-1,-1) and returns the ANSI sequence to reset all text attributes to normal.

    Note that inserting ANSI color sequences in calendar mode will produce garbled results. Therefore, we recommend defining functions such as the ones below that return the empty string in calendar mode:

            IF $CalMode
                FSET fg(r,g,b) ""
                FSET bg(r,g,b) ""
            ELSE
                FSET fg(r,g,b) ansicolor(r,g,b)
                FSET bg(r,g,b) ansicolor(r,g,b,1)
            ENDIF
            REM [fg(255,0,0)][bg(64,64,64)]Red on Gray[fg(-1,-1,-1)] in agenda mode
            REM SPECIAL COLOR 0 255 0 Green in agenda and calendar mode

    If you use the ansicolor function, don't forget to reset the color back to normal with ansicolor(-1,-1,-1) or subsequent reminders will continue to be colored.

args(s_fname)
    Returns the number of arguments expected by the user-defined function fname, or -1 if no such user-defined function exists. Note that this function examines only user-defined functions, not built-in functions. Its main use is to determine whether or not a particular user-defined function has been defined previously. The args() function is available only in versions of Remind from 03.00.04 and up.

asc(s_string)
    Returns an INT that is the ASCII code of the first byte in string. As a special case, asc("") returns 0. For UTF-8 strings, this will return the UTF-8 byte with which the string begins, which is not likely to be very useful.

codepoint(s_string)
    Returns an INT that is the code point of the first character in string, treating multi-byte characters correctly. As a special case, codepoint("") returns 0.

baseyr()
    Returns the "base year" that was compiled into Remind (normally 1990.) All dates are stored internally as the number of days since 1 January of baseyr().

catch(x_arg1, x_arg2)
    Evaluates arg1 and if no error occurs, returns the resulting value. If an error occurs during the evaluation of arg1, evaluates and returns arg2. Note that catch() can only catch run-time evaluation errors. It cannot catch syntax errors.

    Here are some examples:

    catch(4/2, 33)  => 2, because 4/2 evaluates without error
    catch(4/0, 33)  => 33, because 4/0 gives a divide-by-zero error
    catch(2, 1/0)   => 2, and the second argument is not evaluated
    catch(4/0, 1/0) results in a divide-by-zero error

    Note in the last example that catch does not protect you from errors in the evaluation of arg2.

catcherr()
    Returns a string representing the error message from the most recently-evaluated catch() function whose first argument yielded an error. Note that the error message is always in English even if Remind has been localized; this lets you reliably test the return value. Here are some examples:

        # No "catch" invocations yet:  sets a to "Ok"
        set a catcherr()
        # Sets b to "oops" and a to "Division by zero"
        set b catch(1/0, "oops")
        set a catcherr()
        # Sets b to 1 and a to "Division by zero".  The catch error
        # is never cleared by a non-error catch()
        set b catch(4-3, "not-evaluated")
        set a catcherr()

char(i_i1 [,i_i2...])
    This function can take any number of INT arguments. It returns a STRING consisting of the bytes specified by the arguments. It is easy to create invalid UTF-8 sequences; char does not check for this. Note that none of the arguments can be 0, unless there is only one argument. As a special case, char(0) returns "".

mbchar(i_i1 [,i_i2...])
    This function can take any number of INT arguments. It returns a STRING consisting of the characters specified by the arguments. Any codepoint may be supplied and a correct multi-byte character string will be returned. Note that none of the arguments can be 0, unless there is only one argument. As a special case, mbchar(0) returns "". Additionally, no argument may be a negative number.

choose(i_index, x_arg1 [,x_arg2...])
    Choose must take at least two arguments, the first of which is an INT. If index is n, then the nth subsequent argument is returned. If index is less than 1, then arg1 is returned. If index is greater than the number of subsequent arguments, then the last argument is returned. Examples:

		choose(0, "foo", 1:13, 1000) returns "foo"
		choose(1, "foo", 1:13, 1000) returns "foo"
		choose(2, "foo", 1:13, 1000) returns 1:13
		choose(3, "foo", 1:13, 1000) returns 1000
		choose(4, "foo", 1:13, 1000) returns 1000

    Note that only the first argument and the chosen result are evaluated. Any non-chosen arguments will not be evaluated.

coerce(s_type, x_arg)
    This function converts arg to the specified type, if such conversion is possible. Type must be one of "INT", "STRING", "DATE", "TIME" or "DATETIME" (case-insensitive). The conversion rules are as follows:

    If arg is already of the type specified, it is returned unchanged.

    If type is "STRING", then arg is converted to a string consisting of its printed representation.

    If type is "DATE", then an INT arg is converted by interpreting it as the number of days since 1 January baseyr(). A STRING arg is converted by attempting to read it as if it were a printed date. A DATETIME is converted to a date by dropping the time component. A TIME arg cannot be converted to a date.

    If type is "TIME", then an INT arg is converted by interpreting it as the number of minutes since midnight. A STRING arg is converted by attempting to read it as if it were a printed time. A DATETIME is converted to a time by dropping the date component. A DATE arg cannot be converted to a time.

    If type is "DATETIME", then an INT arg is converted by interpreting it as the number of minutes since midnight, 1 January baseyr(). A STRING is converted by attempting to read it as if it were a printed datetime. Other types cannot be converted to a datetime.

    If type is "INT", then DATE, TIME and DATETIME arguments are converted using the reverse of procedures described above. A STRING arg is converted by parsing it as an integer.

columns([s_arg])
    If called with no arguments, columns() behaves as follows: If either standard output or standard error is a TTY, returns the width of the terminal in columns. If neither standard output nor standard error is a TTY, attempts to open "/dev/tty" to obtain the terminal size. If this fails, returns -1.

    If called with a single string argument, columns(str) returns the number of columns str will occupy if printed to a terminal. ANSI color-changing sequences occupy zero columns whereas some Unicode characters occupy two columns. columns(str) takes all of that into account. Note that if Remind was compiled without Unicode support, columns(str) returns a type mismatch error.

    The result of columns(str) may be less than, equal to, or greater than the result of mbstrlen(str). This is because some Unicode characters are so-called combining characters that add one to the character length, but don't occupy any columns on their own. And other Unicode characters are double-width characters that add one to the character length, but two to the number of display columns.

const(x_arg)
    Evaluates arg and returns it, but also ensures that the result is marked "constant". Use with caution; incorrect use could result in unwanted reminders being purged in Purge Mode. See also the section "NON-CONSTANT EXPRESSIONS"

current()
    Returns the current date and time as a DATETIME object. This may be the actual date and time, or may be the date and time supplied on the command line.

date(i_y, si_m, i_d)
    The date() function returns a DATE object with the year, month and day components specified by y, m and d. The month can be specified as an integer from 1 to 12, or a string that is the name of a month.

datepart(dq_datetime)
    Returns a DATE object representing the date portion of datetime.

datetime(args)
    The datetime() function can take anywhere from two to five arguments. It always returns a DATETIME generated from its arguments.

    If you supply two arguments, the first must be a DATE and the second a TIME.

    If you supply three arguments, the first must be a DATE and the second and third must be INTs. The second and third arguments are interpreted as hours and minutes and converted to a TIME.

    If you supply four arguments, they are interpreted as year, month, day and time. Year and day must be INTs. Month may be an INT from 0 to 12 or a string naming a month. Time must be a TIME.

    Finally, if you supply five arguments, they must all be INTs and are interpreted as year, month, day, hour and minute. (Actually, month can also be a string that is the name of a month.)

dawn([dq_date])
    Returns the time of "civil dawn" on the specified date. If date is omitted, defaults to today(). If a datetime object is supplied, only the date component is used.

day(dq_date)
    This function takes a DATE or DATETIME as an argument, and returns an INT that is the day-of-month component of date.

daysinmon(si_m, i_y) or  daysinmon(dq_date)
    Returns the number of days in month m (1-12) of the year y. The first argument can either be an integer from 1 to 12, or a string that is the name of a month. If given a single DATE or DATETIME argument, returns the number of days in the month containing the argument.

defined(s_var)
    Returns 1 if the variable named by var is defined, or 0 if it is not.
    Note that defined() takes a STRING argument; thus, to check if variable X is defined, use:

    		defined("X")

    and not:

    		defined(X)

    The second example will attempt to evaluate X, and will return an error if it is undefined or not of type STRING.

dosubst(s_str [,d_date [,t_time]]) or dosubst(s_str [,q_datetime])
    Returns a STRING that is the result of passing str through the substitution filter described earlier. The parameters date and time (or datetime) establish the effective trigger date and time used by the substitution filter. If date and time are omitted, they default to today() and now().

    Note that if str does not end with "%", a newline character will be added to the end of the result. Also, calling dosubst() with a date that is in the past (i.e., if date < today()) will produce undefined results.

    Dosubst() is only available starting from version 03.00.04 of Remind.

dusk([dq_date])
    Returns the time of "civil twilight" on the specified date. If date is omitted, defaults to today().

easterdate([dqi_arg])
    If arg is an INT, then returns the date of Easter Sunday for the specified year. If arg is a DATE or DATETIME, then returns the date of the next Easter Sunday on or after arg. (The time component of a datetime is ignored.) If arg is omitted, then it defaults to today().

    Note that easterdate computes the Western Easter. For the Orthodox Easter date, see orthodoxeaster.

escape(s_string [,i_add_quotes])
    Returns a STRING that is the same as the input string, but with all special characters backslashed-escaped. For example, the following command:

            set a escape("foo" + char(10) + "bar")

    will set a to "foo\nbar" where "\n" is the literal sequence "\" followed by "n". This is useful if you want to compute a string in a pasted-in expression that Remind will then parse as a quoted string again, such as in a TRANSLATE command or an INFO clause.

    If the optional add_quotes argument is supplied and is non-zero, then the return value from escape will include surrounding double-quotes.

eval(s_arg)
    Parses the string arg as an expression and evaluates it, returning the result. Note that any variable names in the parsed expression refer to global variables, not any local variables. For example, consider this:

            SET x 2
            FSET f(x) x + eval("1 + x")
            REM MSG F is [f(9)]

    The result will be "F is 12" because the reference to x inside the eval() argument refers to the global variable x and not the function argument.

    Note that for safety, RUN is disabled during the evaluation of eval(), which means you can't use the shell() function from within an eval().

evaltrig(s_trigger [,dq_start])
    Evaluates trigger as if it were a REM or IFTRIG trigger specification and returns the trigger date as a DATE (or as a DATETIME if there is an AT clause.) Returns a negative INT if no trigger could be computed.

    Normally, evaltrig finds a trigger date on or after today. If you supply the start argument, then it scans starting from there.

    For example, the expression:

      evaltrig("Mon 1", '2008-10-07')

    returns '2008-11-03', since that is the first date on or after 7 October 2008 that satisfies "Mon 1".

    If you want to see how many days it is from the first Monday in October, 2008 to the first Monday in November, 2008, use:

      evaltrig("Mon 1", '2008-11-01') - evaltrig("Mon 1", '2008-10-01')

    and the answer is 28. The trigger argument to evaltrig can have all the usual trigger clauses (OMIT, AT, SKIP, etc.) but cannot have a SATISFY, MSG, etc. reminder-type clause.

filedate(s_filename)
    Returns the modification date of filename. If filename does not exist, or its modification date is before the year baseyr(), then 1 January of baseyr() is returned.

filedatetime(s_filename)
    Returns the modification date and time of filename. If filename does not exist, or its modification date is before the year baseyr(), then midnight, 1 January of baseyr() is returned.

filedir()
    Returns the directory that contains the current file being processed. It may be a relative or absolute pathname, but is guaranteed to be correct for use in an INCLUDE command as follows:

		INCLUDE [filedir()]/stuff

    This includes the file "stuff" in the same directory as the current file being processed. Note that this workaround is no longer necessary because DO stuff will achieve the same goal.

    Note that if the currently-processing reminders file was specified as a symbolic link, then filedir() returns the directory containing the symbolic link and not the directory containing the target of the symbolic link. You should avoid using symbolic links to files unless both the symbolic link and its target happen to be in the same directory.

filename()
    Returns (as a STRING) the name of the current file being processed by Remind. Inside included files, returns the name of the included file.

getenv(s_envvar)
    Similar to the getenv(2) system call. Returns a string representing the value of the specified environment variable. Returns "" if the environment variable is not defined. Note that the names of environment variables are generally case-sensitive; thus, getenv("HOME") is not the same as getenv("home").

hebdate(i_day, s_hebmon [,idq_yrstart [,i_jahr [,i_aflag]]])
    Support for Hebrew dates - see the section "THE HEBREW CALENDAR"

hebday(dq_date)
    Support for Hebrew dates - see the section "THE HEBREW CALENDAR"

hebmon(dq_date)
    Support for Hebrew dates - see the section "THE HEBREW CALENDAR"

hebyear(dq_date)
    Support for Hebrew dates - see the section "THE HEBREW CALENDAR"

hex(i_n)
    Returns a STRING that is the hexadecimal representation of n. There is no "0x" prefix and any letters in the returned value are uppper-case.

hour(tq_time)
    Returns the hour component of time.

htmlescape(s_str)
    Returns a modified copy of str where "<" is replaced with "&lt;"; ">" is replaced with "&gt;" and "&" is replaced with "&amp;"

htmlstriptags(s_str)
    Returns a modified copy of str where HTML tags are stripped out. The stripping algorithm is fairly naive; the function starts stripping characters when it encounters a "<" and it stops stripping when it encounters a ">".

iif(x_test1, x_arg1, [x_test2, x_arg2,...], x_default)
    If test1 is true, returns arg1. Otherwise, if test2 is true, returns arg2, and so on. If all of the test arguments are false, returns default. Note that only those arguments needed to determine the final result are evaluated. This function accepts an odd number of arguments - note that prior to version 03.00.05 of Remind, it accepted 3 arguments only. The 3-argument version of iif() is compatible with previous versions of Remind.

index(s_search, s_target [,i_start)
    Returns an INT that is the location of target in the string search. Note that index uses byte positions, not character positions, so should not be used on non-ASCII strings. Use mbindex for non-ASCII strings.

    The first byte of a string is numbered 1. If target does not exist in search, then 0 is returned.

    The optional parameter start specifies the position in search at which to start looking for target.

mbindex(s_search, s_target [,i_start])
    Similar to index() but returns the character position rather than the byte position. Also, start is interpreted as a 1-based character index rather than a byte index.

isany(arg1 [,arg2, ..., argN]);
    Returns 1 if the first argument arg1 is equal to any of the subsequent arguments arg2 through argN; returns 0 otherwise. Also returns 0 if called with only one argument.

    As an example, the following two expressions are equivalent:

            (a == b) || (a == c) || (a == d) || (a == e)
            isany(a, b, c, d, e)

isconst(x_any)
    Evaluates its argument and then throws away the value, returning 1 if the expression is constant or 0 if it is non-constant. Note that isconst does not take into account the context; if arg is a constant expression but evaluated in a non-constant context, isconst will still return 1. For details about constant vs. non-constant expressions, see the section "NON-CONSTANT EXPRESSIONS"

isdst([d_date [,t_time]]) or isdst(q_datetime)
    Returns a positive number if daylight saving time is in effect on the specified date and time. Date defaults to today() and time defaults to midnight.

    Note that this function is only as reliable as the C run-time library functions. It is available starting with version 03.00.07 of Remind.

isleap(idq_arg)
    Returns 1 if arg is a leap year, and 0 otherwise. Arg can be an INT, DATE or DATETIME object. If a DATE or DATETIME is supplied, then the year component is used in the test.

isomitted(dq_date)
    Returns 1 if date is omitted, given the current global OMIT context. Returns 0 otherwise. (If a datetime is supplied, only the date part is used.) Note that any local OMIT or OMITFUNC clauses are not taken into account by this function.

language()
    Returns a STRING naming the compiled-in language supported by Remind. Remind used to support compiled-in support for other languages, but now all localization is done at run-time. As such, this function always returns "English". However, the expression _("LANGID") returns the two-character ISO 639 language code of any language pack in effect, assuming the language pack author has written the localization correctly!

localtoutc(q_datetime)
    Given a DATETIME object interpreted in the local time zone, return a DATETIME object that expresses the same time in UTC.

lower(s_string)
    Returns a STRING with all upper-case bytes in string converted to lower-case. Note: This function works correctly only for ASCII strings. If you are using Unicode characters outside the ASCII set, use mblower instead.

mblower(s_string)
    Returns a STRING with all upper-case characters in string converted to lower-case. This function works correctly on any Unicode string.

max(x_arg1 [,x_arg2...)
    Can take any number of arguments, and returns the maximum. The arguments can be of any type, but must all be of the same type. They are compared as with the > operator.

min(x_arg1 [,x_arg2...)
    Can take any number of arguments, and returns the minimum. The arguments can be of any type, but must all be of the same type. They are compared as with the < operator.

minsfromutc([d_date [,t_time]]) or minsfromutc(q_datetime)
    Returns the number of minutes from Universal Time Coordinated (formerly GMT) to local time on the specified date and time. Date defaults to today() and time defaults to midnight. If local time is before UTC, the result is negative. Otherwise, the result is positive.

    Note that this function is only as reliable as the C run-time library functions. It is available starting with version 03.00.07 of Remind.

minute(tq_time)
    Returns the minute component of time.

mon(dqis_arg)
    If arg is of DATE or DATETIME type, returns a string that names the month component of the date. If arg is an INT from 1 to 12, returns a string that names the month. If arg is a STRING, returns the name of the month. This last case might sound silly, but for example:

                 mon("Mar")

    will return "March", the full name of the month.

monnum(dq_date) or monnum(s_str)
    Returns an INT from 1 to 12, representing the month component of date. If a STRING is supplied rather than a DATE or DATETIME, then if str is a valid month name (or minimum 3-character abbreviation of a month name) then the corresponding month number is returned. If str is not a valid month name, then an error occurs.

moondate(i_phase [,d_date [,t_time]]) or moondate(i_phase, q_datetime)
    This function returns the date of the first occurrence of the phase phase of the moon on or after date and time. Phase can range from 0 to 3, with 0 signifying new moon, 1 first quarter, 2 full moon, and 3 third quarter. If date is omitted, it defaults to today(). If time is omitted, it defaults to midnight.

    For example, the following returns the date of the next full moon:

    		SET fullmoon moondate(2)

moontime(i_phase [,d_date [,t_time]]) or moontime(i_phase, q_datetime)
    This function returns the time of the first occurrence of the phase phase of the moon on or after date and time. Phase can range from 0 to 3, with 0 signifying new moon, 1 first quarter, 2 full moon, and 3 third quarter. If date is omitted, it defaults to today(). If time is omitted, it defaults to midnight. Moontime() is intended to be used in conjunction with moondate(). The moondate() and moontime() functions are accurate to within a couple of minutes of the times in "Old Farmer's Almanac" for Ottawa, Ontario.

    For example, the following returns the date and time of the next full moon:

    		MSG Next full moon at [moontime(2)] on [moondate(2)]

moondatetime(i_phase [,d_date [,t_time]]) or moondatetime(i_phase, q_datetime)
    This function is similar to moondate and moontime, but returns a DATETIME result.

moonphase([d_date [,t_time]]) or moonphase(q_datetime)
    This function returns the phase of the moon on date and time, which default to today() and midnight, respectively. The returned value is an integer from 0 to 359, representing the phase of the moon in degrees. 0 is a new moon, 180 is a full moon, 90 is first-quarter, etc.

moonrise([d_date])
    This function returns a DATETIME result giving the date and time of the first moonrise on or after midnight on date. If date is not supplied, it defaults to today().

    Note that it is not uncommon for a day to have no moonrise, so the date part of the return value may not be the same as the date argument. So if you want a calendar of moonrise times, you could use something like this:

        SET mr moonrise()
        IF datepart(mr) == today()
            REM NOQUEUE [mr] MSG Moon rises at %3.
        ELSE
            REM MSG No moonrise today
        ENDIF

moonrisedir([d_date])
    This function returns an INT result giving the direction from which the moon will rise on the first moonrise on or after midnight on date. If date is not supplied, it defaults to today(). The return value ranges from 0 to 359, where 0 is North, 90 is East, 180 is South and 270 is West.

moonset([d_date])
    This function is analogous to moonrise() but returns the DATETIME of the next moonset on or after midnight on date.

moonsetdir([d_date])
    This function is analogous to moonrisedir() but returns the direction of moonset.

multitrig(s_trig1 [,s_trig2, [... s_trigN]])
    multitrig evaluates each string as a trigger, similar to evaltrig, and returns the earliest trigger date that is on or after today(). multitrig is similar to trig but has the following difference:

    trig returns the first trigger date that would have triggered today, whereas multitrig returns the earliest trigger date later than today, regardless of whether it would have triggered today.

    If no trigger can be computed that is later than today(), then multitrig returns 1990-01-01.

    Consider the following examples, assuming that today is Sunday, 24 March 2024:

       # Returns 1990-01-01 because neither would trigger today
       SET a trig("Mon", "Wed")
       # Returns 2024-03-25 because it's the earlier trigger date
       SET a multitrig("Mon", "Wed")
       # Returns 2024-03-27 because it's the first that would trigger today
       SET a trig("Wed +3", "Mon +3")
       # Returns 2024-03-25 because it's the earlier trigger date
       SET a multitrig("Wed +3", "Mon +3")
       # Returns 1990-01-01 because all triggers have expired
       SET a multitrig("2000", "2022", "1998", "2023")

    In general, multitrig works better with the Remind algorithm than trig and should be used most of the time. As an example, this reminder is issued at the end of each quarter:

            REM [multitrig("Mar 31", "Jun 30", "Sep 30", "Dec 31")] +7 MSG \
            %"End of [ord($Tm/3)] quarter%" is %b.

    If you want the last working day of each quarter, you could use:

            PUSH-OMIT-CONTEXT
            OMIT Sat Sun
            REM [multitrig("Mar ~1", "Jun ~1", "Sep ~1", "Dec ~1")] +7 MSG \
            %"Last working day of [ord($Tm/3)] quarter%" is %b.
            POP-OMIT-CONTEXT

    Note that unlike evaltrig, multitrig always returns a DATE and never a DATETIME. Including an AT clause in a trigger supplied to multitrig will result in an error.

ndawn([dq_date])
    Returns the time of "nautical dawn" on the specified date. If date is omitted, defaults to today(). If a datetime object is supplied, only the date component is used.

ndusk([dq_date])
    Returns the time of "nautical twilight" on the specified date. If date is omitted, defaults to today().

nonomitted(dq_start, dq_end [, i_step] [,s_wkday...])
    This function returns the number of non-omitted days between start and end. If start is non-omitted, then it is counted. end is never counted.

    Note that if end is less than start, the arguments are effectively swapped, so counting always begins from the older date.

    If the third argument to nonomitted is an INT, then it must be greater than zero, and is considered to be the step by which nonomitted counts. For example the following expression:

            nonomitted('2023-07-01', '2023-07-29', 7)

    returns the number of non-omitted Saturdays from 2023-07-01 up to (but not including) 2023-07-29. (Both 2023-07-01 and 2023-07-29 are Saturdays.)

    If no step argument is supplied, then a step of 1 is used.

    In addition to using the global OMIT context, you can supply additional arguments that are names of weekdays to be omitted. However, in a REM command, any local OMITFUNC clause is not taken into account by this function.

    For example, the following line sets a to 11 (assuming no global OMITs):

    	set a nonomitted('2007-08-01', '2007-08-16', "Sat", "Sun")

    because Thursday, 16 August 2007 is the 11th working day (not counting Saturday and Sunday) after Wednesday, 1 August 2007.

    nonomitted has various uses. For example, many schools run on a six-day cycle and the day number is not incremented on holidays. Suppose the school year starts with Day 1 on 4 September 2007. The following reminder will label day numbers in a calendar:

       IF today() >= '2007-09-04'
           set daynum nonomitted('2007-09-04', today(), "Sat", "Sun")
           REM OMIT SAT SUN SKIP CAL Day [(daynum % 6) + 1]
       ENDIF

    Obviously, the answer you get from nonomitted depends on the global OMIT context. If you use movable OMITs, you may get inconsistent results.

    Here is a more complex use for nonomitted. My garbage collection follows two interleaved 14-day cycles: One Friday, garbage and paper recycling ("Black Box") are collected. The next Friday, garbage and plastic recycling ("Blue Box") are collected. If any of Monday-Friday is a holiday, collection is delayed until the Saturday. Here's a way to encode these rules:

       fset _garbhol(x) wkdaynum(x) == 5 && nonomitted(x-4, x+1) < 5
       REM 12 November 1999 *14 AFTER OMITFUNC _garbhol MSG Black Box
       REM 19 November 1999 *14 AFTER OMITFUNC _garbhol MSG Blue Box

    Here's how it works: The _garbhol(x) user-defined function returns 1 if and only if (1) x is a Friday and (2) there is at least one OMITted day from the previous Monday up to and including the Friday.

    The first REM statement sets up the 14-day black-box cycle. The AFTER keyword makes it move collection to the Saturday if _garbhol returns 1. The second REM statement sets up the 14-day blue-box cycle with a similar adjustment made by AFTER in conjunction with _garbhol.

nonconst(x_arg)
    Returns the argument arg unchanged, but forces the expression to be considered non-constant. For details, see the section "NON-CONSTANT EXPRESSIONS"

now()
    Returns the current system time, as a TIME type. This may be the actual time, or a time supplied on the command line. Note that in Calendar Mode, now() always returns 00:00.

ord(i_num)
    Returns a string that is the ordinal number num. For example, ord(2) returns "2nd", and ord(213) returns "213th".

    In order to help with localization, if you define a function called ordx that takes a single parameter, then calling ord(n) invokes ordx(n) and returns whatever it does. During the callback to ordx, RUN will be disabled.

orthodoxeaster([dqi_arg])
    If arg is an INT, then returns the date of Orthodox Easter Sunday for the specified year. If arg is a DATE or DATETIME, then returns the date of the next Orthodox Easter Sunday on or after arg. (The time component of a datetime is ignored.) If arg is omitted, then it defaults to today().

    Note that orthodoxeaster computes the Orthodox Easter. For the Western Easter date, see easterdate.

ostype()
    Returns "UNIX". Remind used to run on OS/2 and MS-DOS, but does not any longer.

pad(x_arg, s_padstr, i_len [, i_right])
    Converts the first argument arg to a string if necessary, and then if it is shorter than len bytes, pads to to len bytes using as many copies (including partial copies) of padstr as necessary. By default, the string is left-padded, but if right is supplied and non-zero, the string will be right-padded.

    Here are some examples:

        pad(3, "0", 2)        -->  "03"
        pad(465, "0", 2)      -->  "465"
        pad("foo", " ", 5)    -->  "  foo"
        pad("foo", " ", 5, 1) -->  "foo  "
        pad("foo", "bar", 11) -->  "barbarbafoo"

mbpad(x_arg, s_padstr, i_len [, i_right])
    This is the multibyte counterpart to pad. The length is specified in characters rather than bytes. Use mbpad rather than pad if either of the strings contains non-ASCII characters.

plural(i_num [,s_str1 [,s_str2]])
    Can take from one to three arguments. If one argument is supplied, returns "s" if num is not 1, and "" if num is 1.

    If two arguments are supplied, returns str1 + "s" if num is not 1. Otherwise, returns str1.

    If three arguments are supplied, returns str1 if num is 1, and str2 otherwise.

psmoon(i_phase [,i_size [,s_note [,i_notesize]]])
    [DEPRECATED] Returns a STRING consisting of PostScript code to draw a moon in the upper-left hand corner of the calendar box. Phase specifies the phase of the moon, and is 0 (new moon), 1 (first quarter), 2 (full moon) or 3 (third quarter). If size is specified, it controls the radius of the moon in PostScript units (1/72 inch.) If it is not specified or is negative, the size of the day-number font is used.

    For example, the following four lines place moon symbols on the PostScript calendar:

    		REM [moondate(0)] PS [psmoon(0)]
    		REM [moondate(1)] PS [psmoon(1)]
    		REM [moondate(2)] PS [psmoon(2)]
    		REM [moondate(3)] PS [psmoon(3)]

    If note is specified, the text is used to annotate the moon display. The font is the same font used for calendar entries. If notesize is given, it specifies the font size to use for the annotation, in PostScript units (1/72 inch.) If notesize is not given, it defaults to the size used for calendar entries. (If you annotate the display, be careful not to overwrite the day number -- Remind does not check for this.) For example, if you want the time of each new moon displayed, you could use this in your reminder script:

    	REM [moondate(0)] PS [psmoon(0, -1, moontime(0)+"")]

    Note how the time is coerced to a string by concatenating the null string.

psshade(i_gray) or psshade(i_red, i_green, i_blue)
    [DEPRECATED] Returns a STRING that consists of PostScript commands to shade a calendar box. Num can range from 0 (completely black) to 100 (completely white.) If three arguments are given, they specify red, green and blue intensity from 0 to 100. Here's an example of how to use this:

    		REM Sat Sun PS [psshade(95)]

    The above command emits PostScript code to lightly shade the boxes for Saturday and Sunday in a PostScript calendar.

    Note that psmoon and psshade are deprecated; instead you should use the SPECIAL SHADE and SPECIAL MOON reminders as described in "Out-of-Band Reminders."

realcurrent()
    Returns (as a DATETIME) the true date and time of day as provided by the operating system. This is in contrast to current(), which may return a time supplied on the command line.

realnow()
    Returns the true time of day as provided by the operating system. This is in contrast to now(), which may return a time supplied on the command line, or 00:00 in Calendar Mode.

realtoday()
    Returns the date as provided by the operating system. This is in contrast to Remind's concept of "today", which may be changed if it is running in calendar mode, or if a date has been supplied on the command line.

rows()
    If either standard output or standard error is a TTY, returns the height of the terminal in rows. If neither standard output nor standard error is a TTY, attempts to open "/dev/tty" to obtain the terminal size. If this fails, returns -1.

sgn(i_num)
    Returns -1 if num is negative, 1 if num is positive, and 0 if num is zero.

shell(s_cmd [,i_maxlen])
    Executes cmd as a system command, and returns the first 511 characters of output resulting from cmd. Any whitespace character in the output is converted to a space. Note that if RUN OFF has been executed, or the -r command-line option has been used, shell() will result in an error, and cmd will not be executed.

    When shell runs cmd, it arranges for cmd's standard input file descriptor to be connected to /dev/null.

    If maxlen is specified, then shell() returns the first maxlen characters of output (rather than the first 511). If maxlen is specified as a negative number, then it defaults to the value of the system variable $MaxStringLen.

shellescape(s_str)
    Returns str with all shell metacharacters such as " ", "*", etc escaped with a backslash. For example:

        SET a shellescape("a b*? c&d$e")

    will set a to:

        "a\ b\*\?\ c\&d\$e"

slide(d_start, i_amt [, i_step] [,s_wkday...])
    This function is the inverse of nonomitted. It adds amt (which can be negative) chunks of step days to start, not counting omitted days. If step is not supplied, then it is assumed to be 1. Note that only every stepth day is tested to see if it is omitted. The optional wkday arguments are additional weekday names to omit.

    Consider this example:

    	OMIT 14 May 2009
    	SET a slide('2009-05-13', 5, "Sat", "Sun")

    In this case, a is set to 2009-05-21. That's because we slide forward by 5 days, not including Thursday, May 14 or Saturday and Sunday, May 16 and 17. You can go backwards, too, so:

    	OMIT 14 May 2009
    	SET a slide('2009-05-21', -5, "Sat", "Sun")

    takes a back to 2009-05-13.

    Now consider this example:

            OMIT 14 May 2009
            SET a slide('2009-05-07', 2, 7)

    This sets a to '2009-05-28' because we skip ahead two weeks, not counting a week where the day we land on happens to be omitted. Contrast with this:

            OMIT 13 May 2009
            SET a slide('2009-05-07', 2, 7)

    which sets a to '2009-05-21'. Although 2009-05-13 is omitted, we don't "land" on it as we step forward in chunks of 7 days, so we never see that it is omitted.

soleq(i_which [, dqi_start])
    The soleq function computes solstices and equinoxes. The which parameter ranges from 0 to 3, and specifies which event we are interested in: 0 is the March equinox; 1 is the June solstice; 2 is the September equinox and 3 is the December solstice.

    The optional start parameter can either be an integer specifying the year of the event we are interested in, or a DATE or DATETIME object; if the latter, then soleq returns the first event on or after the date part of the start parameter (it ignores the time component if start is a DATETIME.) If start is not supplied, then it defaults to today().

    The return value of soleq() is a DATETIME object specifying the date and time of the solstice or equinox in the local time zone. It should be accurate to within 3 minutes or so in the worst case.

    See the included file $SysInclude/seasons.rem for examples of how to use soleq().

stdout()
    Returns a string representing where Remind's standard output is going. The return values are one of the following: "TTY" if standard-output is a terminal, "BLOCKDEV" if it is a block device (very unlikely), "CHARDEV" if it is a character device (e.g., /dev/null), "DIR" if it is a directory (very unlikely), "PIPE" if it is a pipe or FIFO, "SYMLINK" if it is a symlink (very unlikely), "SOCKET" if it is a socket, or "UNKNOWN" if it could not be determined.

    The purpose of stdout() is mostly to distinguish between TTY and non-TTY output; you may wish to change or disable colors if the output is not going to a TTY.

strlen(s_str)
    Returns the length of str in bytes. If the length of str is too large to represent as an integer, emits a "Number too high" error. Note that strlen returns the number of bytes in the string, not the number of characters. These numbers are the same for ASCII strings, but may be different for UTF-8 strings.

mbstrlen(str)
    Similar to strlen, but returns the length of the string in characters rather than bytes and is thus safe for use on multi-byte strings.

substr(s_str, i_start [,i_end])
    Returns a STRING consisting of all bytes in str from start up to and including end. Bytes are numbered from 1. If end is not supplied, then it defaults to the length of str. Because substr uses byte indexes rather than character indexes, it should not be used on multi-byte strings.

mbsubstr(s_str, i_start [,i_end])
    Similar to substr but uses character indexes rather than byte indexes, and is thus safe for use on multi-byte strings.

sunrise([dq_date])
    Returns a TIME indicating the time of sunrise on the specified date (default today().) In high latitudes, there may be no sunrise on a particular day, in which case sunrise() returns the INT 0 if the sun never sets, or 1440 if it never rises.

sunset([dq_date])
    Returns a TIME indicating the time of sunset on the specified date (default today().) In high latitudes, there may be no sunset on a particular day, in which case sunset() returns the INT 0 if the sun never rises, or 1440 if it never sets.

    The functions sunrise() and sunset() are based on an algorithm in "Almanac for Computers for the year 1978" by L. E. Doggett, Nautical Almanac Office, USNO. They require the latitude and longitude to be specified by setting the appropriate system variables. (See "System Variables".) The sun functions should be accurate to within about 4 minutes for latitudes lower than 60 degrees. The functions are available starting from version 03.00.07 of Remind.

time(i_hr, i_min)
    Creates a TIME with the hour and minute components specified by hr and min.

timepart(tq_datetime)
    Returns a TIME object representing the time portion of datetime.

timezone([dq_datetime])
    Returns a string representing the local time zone name of the given DATETIME. If no argument is supplied, Remind uses the value of current(). If a DATE rather than DATETIME is supplied, Remind uses a time part of 00:00.

today()
    Returns Remind's notion of "today." This may be the actual system date, or a date supplied on the command line, or (in Calendar Mode) the date of the calendar entry currently being computed.

trig(s_1 [,s_2, ...])
    For each string argument s_n, trig evaluates s_n as if it were a REM or IFTRIG trigger specification. If the trigger would trigger today, then the trigger date is returned and no further triggers are evaluated. If none of the triggers would trigger today, then the zero date 1990-01-01 is returned.
    trig also has a zero-argument form; this returns the trigger date of the most recent trig function that returned a non-zero trigger date.

    trig can be used to make more sophisticated versions of IFTRIG. For example, if you have meetings every Monday in June and July, and you want warnings 3 days in advance, you could use:

        REM [trig("Mon Jun +3", "Mon July +3")] +3 MSG Meeting %b

    NOTE: We need to repeat the +3 delta outside of the trig function for advance warning to work properly. This is because trig returns a date constant (the trigger date) and the REM command does not know the details of trig's arguments.

    Note that because Remind has short-circuit logical operators, something like:

        SET a trig("Mon +7") || trig("Fri +7")
    would set the value of trig() to the date of the following Monday. Because trig("Mon +7") always returns true, the logical-OR operator does not bother evaluating trig("Fri +7") which therefore does not set trig().

    Important Note: Because trig() always returns an absolute date, it will not work properly with a SATISFY clause. Consider this reminder:

        REM [trig("Mar", "Apr")] SATISFY [$Td == 15] MSG 15 Mar or April

    If we run Remind on 5 March 2022, we might expect the trigger date to be calculated as 15 March 2022... but that's not what happens. Instead, the trig function is evaluated first, and it returns 2022-03-05. So as far as Remind is concerned, the REM statement becomes:

        REM 2022-03-05 SATISFY [$Td == 15] MSG 15 Mar or April

    and the SATISFY expression is never true. So: Do not mix trig() and SATISFY.

trigdate()
    Returns the calculated trigger date of the last REM or IFTRIG command. If used in the body of a REM command, returns that command's trigger date. If the most recent REM command did not yield a computable trigger date, returns the integer 0.

trigdatetime()
    Similar to trigdate(), but returns a DATETIME if the most recent triggerable REM command had an AT clause. If there was no AT clause, returns a DATE. If no trigger could be computed, returns the integer 0. See "MULTI-DAY EVENTS" for more information.

trigeventstart()
    Returns a DATETIME representing the start of the most recent triggerable REM command that had an AT clause. For events without a DURATION or that do not span multiple days, returns the same as trigdatetime(). If the REM command did not have an AT clause, returns the integer -1 (and differs from trigdatetime() in this respect.) See "MULTI-DAY EVENTS" for more information.

trigeventstarttz()
    Similar to trigeventstart() but returns the DATETIME in the time zone specified by a TZ clause, if one was present. If no TZ clause was present, returns the same value as trigeventstart().

trigeventduration()
    Returns a TIME representing the duration of the most recent triggerable REM command that had an AT and a DURATION clause. If the event does not span multiple days, returns the same thing as trigduration(). If the REM command lacked an AT or DURATION clause, returns -1. See "MULTI-DAY EVENTS" for more information.

trigback()
    Returns the "back" amount of the last REM or IFTRIG command. Returns a positive integer N if the "back" is of the form -N, or a negative integer if it is of the form --N. If there is no "back", then returns 0.

trigbase()
    Returns the "base" date of the last REM or IFTRIG command. If the trigger specification includes all three of day, month and year, then the base date is the date formed from those components. If the trigger specification lacks one of those components, then 0 is returned.

    Here is an example of how trigbase() might be used:

            REM 2025-05-05 *7 UNTIL 2025-05-26 \
               MSG Meeting: week #[(trigdate() - trigbase())/trigrep()+1]

    On 2025-05-05, it would print: "Meeting: week #1". On 2025-05-12, it would print: "Meeting: week #2" and so on.

trigdelta()
    Returns the "delta" amount of the last REM or IFTRIG command. Returns a positive integer N if the "delta" is of the form +N, or a negative integer if it is of the form ++N. If there is no "delta", then returns 0.

trigtimedelta()
    Similar to trigdelta(), but returns the delta used in the AT clause of a timed reminder.

trigrep()
    Returns the "repeat" amount of the last REM or IFTRIG command. Returns a positive integer N if the "repeat" is of the form *N. If there is no "repeat", then returns 0.

trigtimerep()
    Similar to trigrep(), but returns the repeat used in the AT clause of a timed reminder.

trigtz()
    If a TZ clause was used in the last REM or IFTRIG command, returns the time zone name. Otherwise returns the empty string.

trigduration()
    Returns (as a TIME type) the DURATION parameter of a timed reminder. If there is no DURATION parameter, returns the integer -1. See "MULTI-DAY EVENTS" for more information.

trigpriority()
    Returns the PRIORITY of the last REM or IFTRIG command.

triguntil()
    Returns (as a DATE type) the UNTIL parameter of the last REM or IFTRIG command. If there was no UNTIL parameter, returns the integer -1. If there is a THROUGH parameter, that will be returned by triguntil() since "THROUGH yyyy-mm-dd" is simply syntactic sugar for "*1 UNTIL yyyy-mm-dd".

trigscanfrom()
    Returns (as a DATE type) the SCANFROM parameter of the last REM or IFTRIG command. If there was no SCANFROM parameter, returns the integer -1. Note that FROM and SCANFROM interact; a reminder that has a "FROM yyyy-mm-dd" parameter will act as if it has a SCANFROM parameter whose value is the maximum of "yyyy-mm-dd" and today.

trigfrom()
    Returns (as a DATE type) the FROM parameter of the last REM or IFTRIG command. If there was no FROM parameter, returns the integer -1.

triginfo(s_header)
    Returns a STRING that is the INFO item associated with the header header. The header should not contain a colon. Header name comparisons are case-insensitive.

    For example, the following will assign "At home" to the variable a and the empty string to variable b:

            REM INFO "Location: At home" MSG test
            SET a triginfo("location")
            SET b triginfo("no_such_header")

trigistodo()
    Returns 1 if the last REM command was a TODO type or 0 if not.

trigcompletethrough()
    Returns a DATE object that is the COMPLETE-THROUGH date of the most recent REM command. If there was no COMPLETE-THROUGH date, returns the INT 0.

trigmaxoverdue()
    Returns an INT that is the MAX-OVERDUE value of the most recent REM command. If there was no MAX-OVERDUE clause, returns -1.

trigger(d_date [,t_time [,i_utcflag]]) or trigger(q_datetime [,i_utcflag])
    Returns a string suitable for use in a REM command or a SCANFROM or UNTIL clause, allowing you to calculate trigger dates in advance. Note that in earlier versions of Remind, trigger was required to convert a date into something the REM command could consume. However, in this version of Remind, you can omit it. Normally, the date and time are the local date and time; however, if utcflag is non-zero, the date and time are interpreted as UTC times, and are converted to local time. Examples:

         trigger('1993/04/01')

    returns "1 April 1993",

         trigger('1994/08/09', 12:33)

    returns "9 August 1994 AT 12:33", as does:

         trigger('1994/08/09@12:33').

    Finally:

         trigger('1994/12/01', 03:00, 1)

    returns "30 November 1994 AT 22:00" for EST, which is 5 hours behind UTC. The value for your time zone may differ.

    trigger() will never return a date earlier than "1 January 1990" even if the UTC flag dictates that it should. So do not use it for reminders before about 2 January 1990 in your local time zone. I do not anticipate this restriction being a real problem.

trigtags()
    Returns a comma-separated list of the TAGs associated with the most recent REM command that was triggered. Returns the empty string if there were no TAGs. If there are multiple tags, they are each separated by a single comma, not a comma and a space.

trigtime()
    Returns the time of the last REM command with an AT clause in the system default time zone. If the last REM did not have an AT clause, returns the integer 0. If a REM command has an AT clause with a DURATION, then you can compute the end time as trigtime() + trigduration().

trigtimetz()
    Similar to trigtime() but returns the time in the time zone specified by a TZ clause, if one was present. If no TZ clause was present, returns the same value as trigtime().

trigvalid()
    Returns 1 if the value returned by trigdate() is valid for the most recent REM command, or 0 otherwise. Sometimes REM commands cannot calculate a trigger date. For example, the following REM command can never be triggered:

		REM Mon OMIT Mon SKIP MSG Impossible!

typeof(x_arg)
    Returns "STRING", "INT", "DATE", "TIME" or "DATETIME", depending on the type of arg.

tzconvert(q_datetime, s_srczone [,s_dstzone])
    Converts datetime from the time zone named by srczone to the time zone named by dstzone. If srczone is the empty string, then the default system time zone is used as the source zone. If dstzone is omitted or is the empty string, the default system time zone is used as the destination zone. The return value is a DATETIME. Time zone names are system-dependent; consult your operating system for legal values. Here is an example:

        tzconvert('2007-07-08@01:14', "Canada/Eastern", "Canada/Pacific")
              returns
        2007-07-07@22:14

    If your system includes the directory /usr/share/zoneinfo, Remind will warn you if you use an invalid time zone name for srczone or dstzone. To suppress these warnings, add a "!" to the beginning of the time zone name.

upper(s_string)
    Returns a STRING with all lower-case bytes in string converted to upper-case. Note: This function works correctly only for ASCII strings. If you are using Unicode characters outside the ASCII set, use mbupper instead.

mbupper(s_string)
    Returns a STRING with all lower-case characters in string converted to upper-case. This function works correctly on any Unicode string.

utctolocal(q_datetime)
    Given a DATETIME object interpreted in UTC, return a DATETIME object that expresses the same time in the local time zone.

value(s_varname [,x_default])
    Returns the value of the specified variable. For example, value("X"+"Y") returns the value of variable XY, if it is defined. If XY is not defined, an error results.

    However, if you supply a second argument, it is returned if the varname is not defined. The expression value("XY", 0) will return 0 if XY is not defined, and the value of XY if it is defined. Note that value evaluates the second argument lazily; it is not evaluated if varname is defined.

version()
    Returns a string specifying the version of Remind. For version 06.02.07, returns "06.02.07". It is guaranteed that as new versions of Remind are released, the value returned by version() will strictly increase, according to the rules for string ordering.

weekno([dq_date, [i_wkstart, [i_daystart]]])
    Returns the week number of the year. If no arguments are supplied, returns the ISO 8601 week number for today(). If one argument date is supplied, then returns the ISO 8601 week number for that date. If two arguments are supplied, then wkstart must range from 0 to 6, and represents the first day of the week (with 0 being Sunday and 6 being Saturday.). If wkstart is not supplied, then it defaults to 1. If the third argument daystart is supplied, then it specifies when Week 1 starts. If daystart is less than or equal to 7, then Week 1 starts on the first wkstart on or after January daystart. Otherwise, Week 1 starts on the first wkstart on or after December daystart. If omitted, daystart defaults to 29 (following the ISO 8601 definition.)

wkday(dqi_arg)
    If arg is a DATE or DATETIME, returns a string representing the day of the week of the date. If arg is an INT from 0 to 6, returns the corresponding weekday ("Sunday" to "Saturday").

wkdaynum(dq_date) or wkdaynum(s_str)
    Returns a number from 0 to 6 representing the day-of-week of the specified date. (0 represents Sunday, and 6 represents Saturday.) If a STRING is supplied, then if str is a valid weekday name (or minimum 3-character abbreviation thereof) then the corresponding weekday number is returned. If str is not a valid weekday name, then an error occurs.

year(dq_date)
    Returns a INT that is the year component of date.

MACHINES WITH A 32-BIT TIME_T TYPE
Internally, the standard C library represents times as a time_t type. This is a signed integer type that counts seconds since midnight, 1 January 1970 UTC. If the time_t type is only 32 bits in size, then the C library cannot represent times after 19 January 2038 at 03:14:07 UTC.

To work around this limitation, Remind will "fold" years greater than 2037 to a smaller year that begins on the same day and has the same number of days. This results in a year that's very likely to have the same daylight saving rules as the original year, unless the rules have changed in the interim (in which case the rule change could not even be represented on a 32-bit machine, so it's moot.)

Remind then does UTC-to-local or local-to-UTC conversions with the folded year, and then post-conversion corrects it back. This should give correct results for astronomical functions and conversions between local and UTC time, providing the daylight saving time rules have not changed between the folded year and the original year.

Note that the $FoldYear system variable is no longer that useful; Remind always folds years if it's necessary on a 32-bit system. You can set $FoldYear to 1 to force Remind to fold years even on a 64-bit system, but that's useful only for testing and not for production.

MULTI-DAY EVENTS
If you specify a start time with AT and a duration with DURATION, you can create events that span multiple days. Consider these two REM statements:

    REM 1991-02-13 AT 16:00 DURATION 72:00 MSG 72-hour event
    REM 1991-02-13 THROUGH 1991-02-16 AT 16:00 MSG Four events

The first statement creates a single event that starts on 13 February 1991 at 16:00 and runs through 16 February 1991 at 16:00

The second statements creates four separate events that start at 16:00 on 13, 14, 15 and 16 February 1991 and have indefinite duration.

Remind handles multi-day events specially. These are the rules:

On the first day of a multi-day event, trigdatetime() will return the starting date and time of the event, and trigduration() will return the original DURATION.

On each subsequent day of a multi-day event, trigdatetime() will return midnight on the day in question, and trigduration() will return the remaining duration. Consider this example:

    #!/bin/sh
    remind - 12 feb 1991 '*6' <<'EOF'
    BANNER %
    REM 1991-02-13 AT 16:00 DURATION 72:00 SATISFY 1
    set a trigdatetime()
    set b trigduration()
    set c trigeventstart()
    set d trigeventduration()
    MSG now=[today()] dt=[a] dur=[b] estart=[c] edur=[d]%
    EOF

The output is:

now=1991-02-12 dt=1991-02-13@16:00 dur=72:00 estart=1991-02-13@16:00 edur=72:00
now=1991-02-13 dt=1991-02-13@16:00 dur=72:00 estart=1991-02-13@16:00 edur=72:00
now=1991-02-14 dt=1991-02-14@00:00 dur=64:00 estart=1991-02-13@16:00 edur=72:00
now=1991-02-15 dt=1991-02-15@00:00 dur=40:00 estart=1991-02-13@16:00 edur=72:00
now=1991-02-16 dt=1991-02-16@00:00 dur=16:00 estart=1991-02-13@16:00 edur=72:00
now=1991-02-17 dt=1991-02-13@16:00 dur=72:00 estart=-1 edur=-1

As you see, the trigdatetime() and trigduration() functions return the start time and duration of the remaining portion of a multi-day event, whereas trigeventstart and trigeventduration always return the original start and duration of the multi-day event. Note also that the return value for expired reminders is not reliable; the fact that trigeventstart and trigeventduration return -1 in that case is an implementation artifact.

SELF-OVERLAPPING EVENTS

A multi-day event has the possibility of "overlapping itself". When this happens, Remind prefers the later event (only one copy of an event is ever triggered for a given date.) Consider this example:

   #!/bin/sh
   remind - '*5' 10 Feb 1991 <<'EOF'
   BANNER %
   REM MON at 0:00 DURATION 192:0 MSG [today()] [trigeventstart()] [trigduration()]%
   EOF

The output is:

   1991-02-10 1991-02-04@00:00 48:00
   1991-02-11 1991-02-11@00:00 192:00
   1991-02-12 1991-02-11@00:00 168:00
   1991-02-13 1991-02-11@00:00 144:00
   1991-02-14 1991-02-11@00:00 120:00

Although the event from 1991-02-04 still has 24 hours left on 1991-02-11, the fresh occurrence on 1991-02-11 takes precedences and is the one that is triggered.

I do not recommend constructing self-overlapping multi-day events.

EXPRESSION PASTING

An extremely powerful feature of Remind is its macro capability, or "expression pasting."

In almost any situation where Remind is not expecting an expression, you can "paste" an expression in. To do this, surround the expression with square brackets. For example:

	REM [mydate] MSG foo

This evaluates the expression "mydate", where "mydate" is presumably some pre-computed variable, and then "pastes" the result into the command-line for the parser to process.

If you want a literal "[" character for some reason, simply use "[[". For example:

        REM MSG Here are [[square] brackets!

A formal description of this is: When Remind encounters a "pasted-in" expression, it evaluates the expression, and coerces the result to a STRING. It then substitutes the string for the pasted-in expression, and continues parsing. Note, however, that expressions are evaluated only once, not recursively. Thus, writing:

	["[a+b]"]

causes Remind to read the token "[a+b]". It does not interpret this as a pasted-in expression.

You can use expression pasting almost anywhere. However, there are a few exceptions:

o   If Remind is expecting an expression, as in the SET command, or the IF command, you should not include square brackets. For example, use:

		SET a 4+5
and not:
		SET a [4+5]

o   You cannot use expression pasting for the first token on a line. For example, the following will not work:

		["SET"] a 1

    This restriction is because Remind must be able to unambiguously determine the first token of a line for the flow-control commands (to be discussed later.)

    In fact, if Remind cannot determine the first token on a line, it assumes that it is a REM command. If expression-pasting is used, Remind assumes it is a REM command. Thus, the following three commands are equivalent:

    		REM 12 Nov 1993 AT 13:05 MSG BOO!
    		12 Nov 1993 AT 13:05 MSG BOO!
    		[12] ["Nov " + 1993] AT [12:05+60] MSG BOO!

o   You cannot use expression-pasting to determine the type (MSG, CAL, etc.) of a REM command. You can paste expressions before and after the MSG, etc. keywords, but cannot do something like this:

            REM ["12 Nov 1993 AT 13:05 " + "MSG" + " BOO!"]

    However, as an escape hatch, the sequence SPECIAL type means the same thing as just type where type is one of MSG, MSF, RUN, CAL, PS and PSFILE. This lets you do something like this:

            SET type "MSG"
            REM 12 Nov 2024 SPECIAL [type] Hello

    You can use this to control the types of your reminders based on variables you set, how Remind is invoked, etc.

COMMON PITFALLS WITH EXPRESSION PASTING

Remember that extra spaces are not inserted when an expression is pasted. Thus, something like:

	REM[expr]MSG[expr]

will probably fail.

If you use an expression to calculate a delta or back, ensure that the result is a positive number. Something like:

	REM +[mydelta] Nov 12 1993 MSG foo

will fail if mydelta happens to be negative.

FLOW CONTROL COMMANDS

Remind has commands that control the flow of a reminder script. Normally, reminder scripts are processed sequentially. However, IF and related commands allow you to process files conditionally, and skip sections that you don't want interpreted.

THE IF COMMAND

The IF command has the following form:

	IF expr
		t-command
		t-command...
	ELSE
		f-command
		f-command...
	ENDIF

Note that the commands are shown indented for clarity. Also, the ELSE portion can be omitted. IF commands can be nested up to a depth of 64, across all levels of INCLUDE.

If the expr evaluates to a non-zero INT, a DATE that is not 1990-01-01, a TIME that is not 00:00, a DATETIME that is not 1990-01-01@00:00, or a non-null STRING, then the IF portion is considered true, and the t-commands are executed. If expr evaluates to zero or null, then the f-commands (if the ELSE portion is present) are executed.

Examples:

	IF defined("want_hols")
		INCLUDE /usr/share/remind/holidays
	ENDIF
	IF today() > '1992/2/10'
		set missed_ap "You missed it!"
	ELSE
		set missed_ap "Still have time..."
	ENDIF

THE IFTRIG COMMAND

The IFTRIG command is similar to an IF command, except that it computes a trigger (as in the REM command), and evaluates to true if a corresponding REM command would trigger. Examples:

	IFTRIG 1 Nov
		; Executed on 1 Nov
	ELSE
		; Executed except on 1 Nov
	ENDIF
	IFTRIG 1 -1 OMIT Sat Sun +4
		; Executed on last working day of month,
		; and the 4 working days preceding it
	ELSE
		; Executed except on above days
	ENDIF

Note that the IFTRIG command computes a trigger date, which can be retrieved with the trigdate() function. You can use all of the normal trigger components, such as UNTIL, delta, etc. in the IFTRIG command. However, you cannot use a type specifier such as CAL, MSG or SATISFY; attempting to do so yields a parse error.

USER-DEFINED FUNCTIONS

In addition to the built-in functions, Remind allows you to define your own functions. The FSET command does this for you:

FSET fname(args) expr

Fname is the name of the function, and follows the convention for naming variables. Args is a comma-separated list of arguments, and expr is an expression. expr is not evaluated at the time the function is defined; instead, it is evaluated each time the function is called. Args can be empty, in which case you define a function taking no parameters. Here are some examples:

	FSET double(x) 2*x
	FSET yeardiff(date1, date2) year(date1) - year(date2)
	FSET since(x) ord($Ty - x)

The last function is useful in birthday reminders. For example:

	REM 1 Nov +12 MSG Dean's [since(1984)] birthday is %b.

Dean was born in 1984. The above example, on 1 November 1992, would print:

	Dean's 8th birthday is today.

Similarly, the function is useful in anniversary reminders. For example:

        REM 4 June MSG [since(1989)] anniversary of the Tienanmen Square massacre

Notes:

o   If you access a variable in expr that is not in the list of arguments, the global value (if any) is used.

o   Function and parameter names are significant to 64 characters.

o   The value() function always accesses the global value of a variable, even if it has the same name as an argument. For example:

    		fset func(x) value("x")
    		set x 1
    		set y func(5)

    The above sequence sets y to 1, which is the global value of x.

o   User-defined functions may call other functions, including other user-defined functions. Recursive calls are allowed, but they must terminate (for example, by using a short-circuit operator or function that breaks the recursion) or an error will result after a certain maximum number of recursive calls (by default, 1000.)

o   If a user-defined function has the same name as a built-in function, it is ignored and the built-in function is used. To prevent conflicts with future versions of Remind (which may define more built-in functions), you may wish to name all user-defined functions beginning with an underscore.

o   If a user-defined function is defined in a context where RUN is disabled, then whenever that function is called, RUN will be disabled during its evaluation, even if it is called from a context where RUN is enabled.

To delete a user-defined function, use FUNSET. This takes a space-separated list of user-defined functions to delete. For example, after the command:

        FUNSET myfunc1 otherfunc thirdfunc

it is guaranteed that no user-defined functions named myfunc1, otherfunc or thirdfunc will exist. Remind does not issue an error if you try to FUNSET a nonexistent user-defined function; it simply does nothing in that case.

You can rename a user-defined function with FRENAME. This takes two names: An old name and a new name. Consider this command:

        FRENAME func_a func_b

If func_a does not exist, the command unsets func_b if it is defined. However, if func_a exists, then it is renamed to func_b, and func_a is no longer defined. If func_b was defined prior to the FRENAME command, then that old definition is lost.

If either argument to the FRENAME command is the name of a built-in function, the command fails with an error message and does nothing.

If you define a user-defined function and then later on redefine it, Remind will issue a warning. If you do not want this warning, then use FUNSET to remove the existing definition before you redefine the function. Alternatively, you can use a "-" token before the function name to suppress "redefined function" warnings, as in the following example:

        FSET - f(x) 2*x
        # You must have space before and after the "-"
        # This will NOT work:
        # FSET -f(x) 2*x

SAVING AND RESTORING FUNCTIONS

Occasionally, it is useful to redefine a function for a specific block of reminders, but to restore its original definition at the end of that block. Just as with variables, functions can be pushed onto and popped off an internal stack. Here is an example:

        PUSH-FUNCS msgprefix
        FSET msgprefix(x) "My new prefix: "
        INCLUDE block_of_reminders.rem
        POP-FUNCS

The file block_of_reminders.rem would be executed with the msgprefix function defined above. After the POP-FUNCS msgprefix would be restored to its previous definition if it had one, or simply unset if it was not previously defined.

The command PUSH-FUNCS takes a space-separated list of function names. All of the named user-defined functions will be saved to an internal stack. You can even push names that are not defined as any function.

After a function name has been pushed, Remind will not issue a warning if you redefine it, because presumably the purpose of pushing it in the first place is to redefine it.

The command POP-FUNCS restores the definitions of all the user-defined functions in the corresponding PUSH-FUNCS command. If undefined functions were pushed onto the stack, then POP-FUNCS makes those functions undefined again. Here's one more example:

        FUNSET a
        FSET b(x) 2*x
        REM MSG [b(3)]   # Outputs 6
        PUSH-FUNCS a b
        FSET a(x) 22*x
        FSET b(x) 3*x
        REM MSG [a(3)] [b(3)] # Outputs 66 9
        POP-FUNCS
        REM MSG [a(3)]   # Undefined function "a"
        REM MSG [b(3)]   # Outputs 6

PRECISE SCHEDULING

The WARN keyword allows precise control over advance warning in a more flexible manner than the delta mechanism. It should be followed by the name of a user-defined function, warn_function.

If a warn_function is supplied, then it must take one argument of type INT. Remind ignores any delta, and instead calls warn_function successively with the arguments 1, 2, 3, ...

Warn_function's return value n is interpreted as follows:

o   If n is positive, then the reminder is triggered exactly n days before its trigger date.

o   If n is negative, then it is triggered n days before its trigger date, not counting OMITted days.

As an example, suppose you wish to be warned of American Independence Day 5, 3, and 1 days in advance. You could use this:

	FSET _wfun(x) choose(x, 5, 3, 1, 0)
	REM 4 July WARN _wfun MSG American Independence Day is %b.

NOTES

1   If an error occurs during the evaluation of warn_function, then Remind stops calling it and simply issues the reminder on its trigger date.

2   If the absolute-values of the return values of warn_function are not monotonically decreasing, Remind stops calling it and issues the reminder on its trigger date.

3   Warn_function should (as a matter of good style) return 0 as the final value in its sequence of return values. However, a reminder will always be triggered on its trigger date, regardless of what warn_function does.

Similarly to WARN, the SCHED keyword allows precise control over the scheduling of timed reminders. It should be followed by the name of a user-defined function, sched_function. Note that if you use SCHED, then any tdelta and trep are ignored.

If a scheduling function is supplied, then it must take one argument of type INT. Rather than using the AT time, time delta, and time repeat, Remind calls the scheduling function to determine when to trigger the reminder. The first time the reminder is queued, the scheduling function is called with an argument of 1. Each time the reminder is triggered, it is re-scheduled by calling the scheduling function again. On each call, the argument is incremented by one.

The return value of the scheduling function must be an INT or a TIME. If the return value is a TIME, then the reminder is re-queued to trigger at that time. If it is a positive integer n, then the reminder is re-queued to trigger at the previous trigger time plus n minutes. Finally, if it is a negative integer or zero, then the reminder is re-queued to trigger n minutes before the AT time. Note that there must be an AT clause for the SCHED clause to do anything.

Here's an example:

	FSET _sfun(x) choose(x, -60, 30, 15, 10, 3, 1, 1, 1, 1, 0)
	REM AT 13:00 SCHED _sfun MSG foo

The reminder would first be triggered at 13:00-60 minutes, or at 12:00. It would next be triggered 30 minutes later, at 12:30. Then, it would be triggered at 12:45, 12:55, 12:58, 12:59, 13:00, 13:01 and 13:02.

NOTES

1   If an error occurs during the evaluation of sched_func, then Remind reverts to using the AT time and the delta and repeat values, and never calls sched_func again.

2   If processing sched_func yields a time earlier than the current system time, it is repeatedly called with increasing argument until it yields a value greater than or equal to the current time. However, if the sequence of values calculated during the repetition is not strictly increasing, then Remind reverts to the default behaviour and never calls sched_func again.

3   It is quite possible using sched_func to keep triggering a reminder even after the AT-time. Also, it is quite possible to not trigger a reminder on the AT time when you use a scheduling function. However, if your scheduling function is terminated (for reasons 1 and 2) before the AT time of the reminder, it will be triggered at the AT time, because normal processing takes over.

4   Your scheduling functions should (as a matter of good style) return 0 when no more scheduling is required. See the example.

5   All scheduling functions are evaluated after the entire Remind script has been read in. So whatever function definitions are in effect at the end of the script are used.

THE SATISFY CLAUSE

The form of REM that uses SATISFY is as follows:

REM trigger SATISFY expr

The way this works is as follows: Remind first calculates a trigger date, in the normal fashion. Next, it sets trigdate() to the calculated trigger date. It then evaluates expr. If the result is not the null string or zero, processing ends. Otherwise, Remind computes the next trigger date, and re-tests expr. This iteration continues until expr evaluates to non-zero or non-null, or until the iteration limit specified with the -x command-line option is reached.

If expr is not satisfied, then trigvalid() is set to 0 and the error message "Can't compute trigger" is issued. Otherwise, trigvalid() is set to 1.

This is really useful only if expr involves a call to the trigdate() or related functions or system variables; otherwise, expr will not change as Remind iterates. In fact, if expr is not a constant and does not call trigdate() or related functions or system variables, then Remind will issue a warning.

An example of the usefulness of SATISFY: Suppose you wish to be warned of every Friday the 13th. Your first attempt may be:

	# WRONG!
	REM Fri 13 +2 MSG Friday the 13th is %b.

But this won't work. This reminder triggers on the first Friday on or after the 13th of each month. The way to do it is with a more complicated sequence:

	REM 13 SATISFY wkdaynum(trigdate()) == 5
	IF trigvalid()
		REM [trigdate()] +2 MSG \
		Friday the 13th is %b.
	ENDIF

You can write the REM statement a little more concisely:

	REM 13 SATISFY $Tw == 5

Let's see how this works. The SATISFY clause iterates through all the 13ths of successive months, until a trigger date is found whose day-of-week is Friday (== 5). If a valid date was found, we use the calculated trigger date to set up the next reminder.

We could also have written:

	REM Fri SATISFY day(trigdate()) == 13

but this would result in more iterations, since "Fridays" occur more often than "13ths of the month."

Here is another example: Suppose you want to be reminded of something on the 15th of January, April, July, and October. You could make four separate reminders, or you could use:

        REM 15 SATISFY [isany($Tm, 1, 4, 7, 10)] MSG 15th Reminder!

This technique of using one REM command to calculate a trigger date to be used by another command is quite powerful. For example, suppose you wanted to OMIT Labour day, which is the first Monday in September. You could use:

	# Note: SATISFY 1 is an idiom for "do nothing"
	REM Mon 1 Sept SATISFY 1
	OMIT [trigdate()]

CAVEAT: This only omits the next Labour Day, not all Labour Days in the future. This could cause strange results, as the OMIT context can change depending on the current date. For example, if you use the following command after the above commands:

	REM Mon AFTER msg hello

the result will not be as you expect. Consider producing a calendar for September, 1992. Labour Day was on Monday, 7 September, 1992. However, when Remind gets around to calculating the trigger for Tuesday, 8 September, 1992, the OMIT command will now be omitting Labour Day for 1993, and the "Mon AFTER" command will not be triggered. (But see the description of SCANFROM in the section "DETAILS ABOUT TRIGGER COMPUTATION.")

It is probably best to stay away from computing OMIT trigger dates unless you keep these pitfalls in mind.

For versions of Remind starting from 03.00.07, you can include a MSG, RUN, etc. clause in a SATISFY clause as follows:

	REM trigger_stuff SATISFY [expr] MSG body

Note that for this case only, the expr after SATISFY must be enclosed in square brackets. It must come after all the other components of the trigger, and immediately before the MSG, RUN, etc. keyword. If expr cannot be satisfied, then the reminder is not triggered.

Thus, the "Friday the 13th" example can be expressed more compactly as:

	REM 13 +2 SATISFY [$Tw == 5] MSG Friday the 13th is %b.

And you can trigger a reminder on Mondays, Wednesdays and Thursdays occurring on odd-numbered days of the month with the following:

	REM Mon Wed Thu SATISFY [$Td %2 ] MSG Here it is!!!

Note that SATISFY and OMITFUNC can often be used to solve the same problem, though in different ways. Sometimes a SATISFY is cleaner and sometimes an OMITFUNC; experiment and use whichever seems clearer.

POSSIBLY-UNCOMPUTABLE TRIGGERS

Occasionally, you may wish to suppress the "Can't compute trigger" warnings for reminders for which a trigger date cannot be computed. For example, the following reminder is triggered on a Monday that is not a holiday if the following Tuesday is a holiday:

        REM Mon SKIP SATISFY [isomitted($T+1)] MSG Work between holidays

However, if there are no Mondays after today's date that satisfy the condition, Remind will print the "Can't compute trigger" error. To suppress this, use the MAYBE-UNCOMPUTABLE keyword:

        REM MAYBE-UNCOMPUTABLE Mon SKIP SATISFY [isomitted($T+1)] MSG Work between holidays

It's almost never appropriate to use MAYBE-UNCOMPUTABLE, but it is provided for those rare occasions when it makes sense. If you use MAYBE-UNCOMPUTABLE inside the evaltrig() function, then untriggerable triggers return -1. For example:

        SET a evaltrig("MAYBE-UNCOMPUTABLE Mon SKIP OMIT Mon")

will set a to -1.

DEBUGGING REMINDER SCRIPTS

Although the command-line -d option is useful for debugging, it is often overkill. For example, if you turn on the -dx option for a reminder file with many complex expressions, you'll get a huge amount of output. The DEBUG command allows you to control the debugging flags under program control. The format is:

DEBUG [+flagson] [-flagsoff]

Flagson and flagsoff consist of strings of the characters "shextvlfqnu" that correspond to the debugging options discussed in the command-line options section. If preceded with a "+", the corresponding group of debugging options is switched on. Otherwise, they are switched off. For example, you could use this sequence to debug a complicated expression:

	DEBUG +x
	set a very_complex_expression(many_args)
	DEBUG -x

THE DUMPVARS COMMAND

The command DUMPVARS displays the values of variables in memory. Its format is:

DUMPVARS [-c] [var...]

If you supply a space-separated list of variable names, the corresponding variables are displayed. If you do not supply a list of variables, then all variables in memory are displayed. To dump a system variable, put its name in the list of variables to dump. If you put a lone dollar sign in the list of variables to dump, then all system variables will be dumped.

If you supply the -c flag, then any variable determined to be constant will have its value followed by "<const>"

THE ERRMSG COMMAND

The ERRMSG command has the following format:

ERRMSG body

The body is passed through the substitution filter (with an implicit trigger date of today()) and printed to the error output stream. Example:

	IF !defined("critical_var")
		ERRMSG You must supply a value for "critical_var"
		EXIT
	ENDIF

THE EXIT COMMAND

The above example also shows the use of the EXIT command. This causes an unconditional exit from script processing. Any queued timed reminders are discarded. If you are in calendar mode (described next), then the calendar processing is aborted.

If you supply an INT-type expression after the EXIT command, it is returned to the calling program as the exit status. Otherwise, an exit status of 99 is returned.

THE FLUSH COMMAND

This command simply consists of the word FLUSH on a line by itself. The command flushes the standard output and standard error streams used by Remind. This is not terribly useful to most people, but may be useful if you run Remind as a subprocess of another program, and want to use pipes for communication.

AGENDA MODE JSON OUTPUT

If you supply the --json argument, then Remind outputs JSON instead of the normal text output. The JSON output consists of a single JSON array of zero or more objects. There are three possible types of objects in the array:

banner
    The banner object, if present, will be the first object in the array. There will be at most one banner object. It contains a single key, banner, whose value is the banner that Remind would normally print in Agenda Mode.

noreminders
    The noreminders object, if present, will be the final object in the array. There will be at most one noreminders object. It contains a single keym, noreminders, whose value is the phrase "No reminders.", possibly localized into a different language.

event
    All other objects in the array are event objects. They are JSON objects that contain all of the keys described in the rem2ps(1) man page section "CALENDAR ENTRIES". However, the calendar_body, plain_body and raw_body keys will not be present.

JSON output can be used by a front-end to display an attractive list of reminders in Agenda Mode. The "show today's reminders" feature of tkremind uses the JSON output.

CALENDAR MODE

If you supply the -c, -s or -p command-line option, then Remind runs in "calendar mode." In this mode, Remind interprets the script repeatedly, performing one iteration through the whole file for each day in the calendar. Reminders that trigger are saved in internal buffers, and then inserted into the calendar in the appropriate places.

If you also supply the -a option, then Remind will not include timed reminders in the calendar.

The -p option is used in conjunction with the Rem2PS program to produce a calendar in PostScript format. For example, the following command will send PostScript code to standard output:

	remind -p .reminders | rem2ps

You can print a PostScript calendar by piping this to the lpr command.

If you have a reminder script called ".reminders", and you execute this command:

	remind -c .reminders jan 1993

then Remind executes the script 31 times, once for each day in January. Each time it executes the script, it increments the value of today(). Any reminders whose trigger date matches today() are entered into the calendar.

MSG and CAL-type reminders, by default, have their entire body inserted into the calendar. RUN-type reminders are not normally inserted into the calendar. However, if you enclose a portion of the body in the %"...%" sequence, only that portion is inserted. For example, consider the following:

	REM 6 Jan MSG %"Dianne's birthday%" is %b

In agenda mode, Remind would print "Dianne's birthday is today" on 6 January. However, in the calendar mode, only the text "Dianne's birthday" is inserted into the box for 6 January.

If you explicitly use the %"...%" sequence in a RUN-type reminder, then the text between the delimiters is inserted into the calendar. If you use the sequence %"%" in a MSG or CAL-type reminder, then no calendar entry is produced for that reminder.

PRESERVING VARIABLES

Because Remind iterates through the script for each day in the calendar, slow operations may severely reduce the speed of producing a calendar.

For example, suppose you set the variables "me" and "hostname" as follows:

	SET me shell("whoami")
	SET hostname shell("hostname")

Normally, Remind clears all variables between iterations in calendar mode and between iterations if a '*N' parameter was supplied on the command-line. However, if certain variables are slow to compute, and will not change between iterations, you can "preserve" their values with the PRESERVE command. Also, since function definitions are preserved between iterations, there is no need to redefine them on each iteration. Thus, you could use the following sequence:

	IF ! defined("initialized")
		set initialized 1
		set me shell("whoami")
		set hostname shell("hostname")
		fset func(x) complex_expr
		preserve initialized me hostname
	ENDIF

The operation is as follows: On the first iteration through the script, "initialized" is not defined. Thus, the commands between IF and ENDIF are executed. The PRESERVE command ensures that the values of initialized, me and hostname are preserved for subsequent iterations. On the next iteration, the commands are skipped, since initialized has remained defined. Thus, time-consuming operations that do not depend on the value of today() are done only once.

Most system variables (those whose names start with '$') are automatically preserved between calendar iterations.

Note that for efficiency, Remind caches the reminder script (and any INCLUDEd files) in memory when producing a calendar.

Timed reminders are sorted and placed into the calendar in time order. These are followed by non-timed reminders. Remind automatically places the time of timed reminders in the calendar according to the -b command-line option. Reminders in calendar mode are sorted as if the -g option had been used; you can change the sort order in calendar mode by explicitly using the -g option to specify a different order from the default.

REPEATED EXECUTION

If you supply a repeat parameter on the command line, and do not use the -c, -p, or -s options, Remind operates in a similar manner to calendar mode. It repeatedly executes the reminder script, incrementing today() with each iteration. The same rules about preserving variables and function definitions apply. Note that using repeat on the command line also enables the -q option and disables any -z option. As an example, if you want to see how Remind will behave for the next week, you can type:

	remind .reminders '*7'

If you want to print the dates of the next 1000 days, use:

	(echo 'banner %'; echo 'msg [today()]%') | remind - '*1000'

INITIALIZING VARIABLES ON THE COMMAND LINE

The -i option is used to initialize variables on the Remind command line. The format is -ivar=expr, where expr is any valid expression. Note that you may have to use quotes or escapes to prevent the shell from interpreting special characters in expr. You can have as many -i options as you want on the command line, and they are processed in order. Thus, if a variable is defined in one -i option, it can be referred to by subsequent -i options.

Note that if you supply a date on the command line, it is not parsed until all options have been processed. Thus, if you use today() in any of the -i expressions, it will return the same value as realtoday() and not the date supplied on the command line.

Any variables defined on the command line are preserved as with the PRESERVE command.

You should not have any spaces between the -i option and the equal sign; otherwise, strange variable names are created that can only be accessed with the value() or defined() functions.

You can also define a function on the command line by using:

-ifunc(args)=definition

Be sure to protect special characters from shell interpretation.

MORE ABOUT POSTSCRIPT

The PS and PSFILE reminders pass PostScript code directly to the printer. They differ in that the PS-type reminder passes its body directly to the PostScript output (after processing by the substitution filter) while the PSFILE-type's body should simply consist of a filename. The Rem2PS program will open the file named in the PSFILE-type reminder, and include its contents in the PostScript output.

The PostScript-type reminders for a particular day are included in the PostScript output in sorted order of priority. Note that the order of PostScript commands has a major impact on the appearance of the calendars. For example, PostScript code to shade a calendar box will obliterate code to draw a moon symbol if the moon symbol code is placed in the calendar first. For this reason, you should not provide PS or PSFILE-type reminders with priorities; instead, you should ensure that they appear in the reminder script in the correct order. PostScript code should draw objects working from the background to the foreground, so that foreground objects properly overlay background ones. If you prioritize these reminders and run the script using descending sort order for priorities, the PostScript output will not work.

All of the PostScript code for a particular date is enclosed in a save-restore pair. However, if several PostScript-type reminders are triggered for a single day, each section of PostScript is not enclosed in a save-restore pair - instead, the entire body of included PostScript is enclosed.

PostScript-type reminders are executed by the PostScript printer before any regular calendar entries. Thus, regular calendar entries will overlay the PostScript-type reminders, allowing you to create shaded or graphical backgrounds for particular days.

Before executing your PostScript code, the origin of the PostScript coordinate system is positioned to the bottom left-hand corner of the "box" in the calendar representing today(). This location is exactly in the middle of the intersection of the bottom and left black lines delineating the box - you may have to account for the thickness of these lines when calculating positions.

Several PostScript variables are available to the PostScript code you supply. All distance and size variables are in PostScript units (1/72 inch.) The variables are:

LineWidth
    The width of the black grid lines making up the calendar.

Border
    The border between the center of the grid lines and the space used to print calendar entries. This border is normally blank space.

BoxWidth and BoxHeight
    The width and height of the calendar box, from center-to-center of the black gridlines.

InBoxHeight
    The height from the center of the bottom black gridline to the top of the regular calendar entry area. The space from here to the top of the box is used only to draw the day number.

/DayFont, /EntryFont, /SmallFont, /TitleFont and /HeadFont
    The fonts used to draw the day numbers, the calendar entries, the small calendars, the calendar title (month, year) and the day-of-the-week headings, respectively.

DaySize, EntrySize, TitleSize and HeadSize
    The sizes of the above fonts. (The size of the small calendar font is not defined here.) For example, if you wanted to print the Hebrew date next to the regular day number in the calendar, use:

	REM PS Border BoxHeight Border sub DaySize sub moveto \
	   /DayFont findfont DaySize scalefont setfont \
	   ([hebday(today())] [hebmon(today())]) show

    Note how /DayFont and DaySize are used.

Note that if you supply PostScript code, it is possible to produce invalid PostScript files. Always test your PostScript thoroughly with a PostScript viewer before sending it to the printer. You should not use any document structuring comments in your PostScript code.

DAEMON MODE

If you use the -z command-line option, Remind runs in "daemon mode". In this mode, no "normal" reminders are issued. Instead, only timed reminders are collected and queued, and are then issued whenever they reach their trigger time.

In addition, Remind wakes up every few minutes to check the modification date on the reminder script (the filename supplied on the command line.) If Remind detects that the script has changed, it re-executes itself in daemon mode, and interprets the changed script. If Remind was compiled with support for inotify(7), then if the command-line reminder script is really a directory, Remind also re-executes itself if any of the files in the directory is changed.

In daemon mode, Remind also re-reads the remind script when it detects that the system date has changed.

In daemon mode, Remind acts as if the -f option had been used, so to run in daemon mode in the background, use:

	remind -z .reminders &

If you use sh or bash, you may have to use the "nohup" command to ensure that the daemon is not killed when you log out.

PURGE MODE

If you supply the -j command-line option, Remind runs in purge mode. In this mode, it tries to purge expired reminders from your reminder files.

In purge mode, Remind reads your reminder file and creates a new file by appending ".purged" to the original file name. Note that Remind never edits your original file; it always creates a new .purged file.

If you invoke Remind against a directory instead of a file, then a .purged file is created for each *.rem file in the directory.

Normally, Remind does not create .purged files for INCLUDed files. However, if you supply a numeric argument after -j, then Remind will create .purged files for the specified level of INCLUDE. For example, if you invoke Remind with the argument -j2, then .purged files will be created for the file (or directory) specified on the command line, any files included by them, and any files included by those files. However, .purged files will not be created for third-or-higher level INCLUDE files.

Determining which reminders have expired is extremely tricky. Remind does its best, but you should always compare the .purged file to the original file and hand-merge the changes back in.

Remind annotates the .purged file as follows:

An expired reminder is prefixed with: #!P: Expired:

In situations where Remind cannot reliably determine that something was expired, you may see the following comments inserted before the problematic line:

   #!P: Cannot purge SATISFY-type reminders
   #!P: The next IF evaluated false...
   #!P: REM statements in IF block not checked for purging.
   #!P: The previous IF evaluated true.
   #!P: REM statements in ELSE block not checked for purging
   #!P: The next IFTRIG did not trigger.
   #!P: REM statements in IFTRIG block not checked for purging.
   #!P: Next line has expired, but contains expression...  please verify
   #!P: Next line may have expired, but contains non-constant expression
   #!P: or a relative SCANFROM clause
   #!P! Could not parse next line: Some-Error-Message-Here
   #!P! Problem calculating trigger date

Remind always annotates .purged files with lines beginning with "#!P". If such lines are encountered in the original file, they are not copied to the .purged file.

If you use the "Hush" flag -h in conjunction with the "Purge" flag -j, then Remind does not create any of the diagnostic comments listed above. Instead, the only change it makes to the .purged file is to mark expired reminders with "#!P: Expired".

NON-CONSTANT EXPRESSIONS

In Purge Mode, Remind will not mark a REM statement as expired if its trigger specification contains a non-constant expression. A non-constant expression is defined as one whose value might differ from run to run, usually because it depends on the current date, but also if it depends on something from the environment (such as the output of the shell() function.)

The use of any of the following in an expression causes Remind to consider it non-constant:

    o   A global variable that has been assigned the result of a non-constant expression, or that has been assigned a value in a non-constant context (to be described later.)

    o   A system variable

    o   Certain built-in functions that depend on the current date (for example, today()) or the environment (for example, shell()).

In addition, for the purposes of safely expiring reminders in Purge Mode, Remind considers the following to be non-constant:

    o   The use of an OMITFUNC

    o   The use of a relative SCANFROM

Whenever a variable is assigned a value, Remind tracks whether or not the expression whose value it was assigned is constant or non-constant. Additionally, variables that are assigned in a non-constant context are always assumed to be non-constant. A non-constant context is the code in the scope of an IF statement where the IF expression is non-constant.

Here are some examples that should make things clear:

        SET d '2025-06-01'        # d is constant
        REM [d] MSG Hello!        # eligible for purging
        SET d today() - 3         # d is non-constant
        REM [d] MSG Hello!        # not eligible for purging
        IF wkdaynum(today()) == 3
            set d '2025-06-01'    # d is non-constant
        ELSE
            set d '2026-01-01'    # d is non-constant
        ENDIF
        SET d '2025-06-01'        # d is constant
        IF today() > today() + 3  # This branch is never taken, but...
            SET d '2029-01-01'    # d is still marked non-constant
        ENDIF
        # Although here d is still '2025-06-01', it is marked
        # non-constant because as far as Remind is concerned,
        # the IF body *might* have been executed depending on today()

Note that within the IF...ENDIF scope, any assignments are non-constant because the code flow depends on today's date, which could change in subsequent Remind runs. If you want to force a variable to be treated as constant, no matter what, then use the following just before you use the variable:

        SET var const(var)

Variables initialized on the command-line with the -i flag are always considered to be non-constant.

If you have an expired reminder that for some reason you never want purged, simply use the built-in function nonconst somewhere in the trigger. For example:

        REM 1992-01-01 MSG This will be purged after Jan 1 1992
        REM [nonconst('1992-01-01')] MSG This will never be purged
        REM Wed UNTIL 1993-12-31 MSG This will be purged after 1993
        REM Wed UNTIL [nonconst('1993-12-31')] MSG Never purged

The n debugging flag prints a message to standard error whenever Remind decides that an expression is non-constant. This can produce a large amount of output, so if you want to find out why Remind considers a specific expression to be non-constant, it's best to use DEBUG +n before it and DEBUG -n after it to limit the amount of output.

SORTING REMINDERS

The -g option causes Remind to sort reminders by trigger date, time and priority before issuing them. Note that reminders are still calculated in the order encountered in the script. However, rather than being issued immediately, they are saved in an internal buffer. When Remind has finished processing the script, it issues the saved reminders in sorted order. The -g option can be followed by up to four characters that must all be "a" or "d". The first character specifies the sort order by trigger date (ascending or descending), the second specifies the sort order by trigger time and the third specifies the sort order by priority. If the fourth character is "d", the untimed reminders are sorted before timed reminders. The default is to sort all fields in ascending order and to sort untimed reminders after timed reminders.

In ascending order, reminders are issued with the most imminent first. Descending order is the reverse. Reminders are always sorted by trigger date, and reminders with the same trigger date are then sorted by trigger time. If two reminders have the same date and time, then the priority is used to break ties. Reminders with the same date, time and priority are issued in the order they were encountered.

You can define a user-defined function called SORTBANNER that takes one DATE-type argument. In sort mode, the following sequence happens:

If Remind notices that the next reminder to issue has a different trigger date from the previous one (or if it is the first one to be issued), then SORTBANNER is called with the trigger date as its argument. The result is coerced to a string, and passed through the substitution filter with the appropriate trigger date. The result is then displayed.

Here's an example - consider the following fragment:

	# Switch off the normal banner
	BANNER %
	REM 11 March 1993 ++1 MSG Not so important
	REM 17 March 1993 ++7 MSG Way in the future
	REM 10 March 1993 MSG Important Reminder
	REM 11 March 1993 ++1 MSG Not so important - B
	FSET sortbanner(x) iif(x == today(), \
		"***** THINGS TO DO TODAY *****", \
		"----- Things to do %b -----")

Running this with the -gaa option on 10 March 1993 produces the following output:

	***** THINGS TO DO TODAY *****
	Important Reminder
	----- Things to do tomorrow -----
	Not so important
	Not so important - B
	----- Things to do in 7 days' time -----
	Way in the future

You can use the args() built-in function to determine whether or not SORTBANNER has been defined. (This could be used, for example, to provide a default definition for SORTBANNER in a system-wide file included at the end of the user's file.) Here's an example:

	# Create a default sortbanner function if it hasn't already
	# been defined
	if args("sortbanner") != 1
		fset sortbanner(x) "--- Things to do %b ---"
	endif

MSGPREFIX() AND MSGSUFFIX()

You can define two functions in your script called msgprefix() and msgsuffix(). They should each accept one argument, a number from 0 to 9999.

In agenda mode, for MSG- and MSF-type reminders, the following sequence occurs when Remind triggers a reminder:

o   If msgprefix() is defined, it is evaluated with the priority of the reminder as its argument. The result is printed. It is not passed through the substitution filter.

o   The body of the reminder is printed.

o   If msgsuffix() is defined, it is evaluated with the priority of the reminder as its argument. The result is printed. It is not passed through the substitution filter.

Here's an example: The following definition causes priority-0 reminders to be preceded by "URGENT", and priority-6000 reminders to be preceded by "(not important)".

	fset msgprefix(x) iif(x==0, "URGENT: ", \
	     x==6000, "(not important) ", "")

In Calendar Mode (with the -c, -s or -p options), an analogous pair of functions named calprefix() and calsuffix() can be defined. They work with all reminders that produce an entry in the calendar (i.e., CAL- and possibly RUN-type reminders as well as MSG-type reminders.)

NOTES

Normally, the body of a reminder is followed by a carriage return. Thus, the results of msgsuffix() will appear on the next line. If you don't want this, make sure the output of msgsuffix begins with a backspace. This places the suffix before rather than after the carriage return. (The backspace character itself is stripped out.) Here is an example:

        FSET msgsuffix(x) char(8) + " - suffix on same line"

If Remind has problems evaluating msgprefix(), msgsuffix() or sortbanner(), you will see a lot of error messages. For an example of this, define the following:

	fset msgprefix(x) x/0

COMPILE-TIME SUPPORT FOR OTHER LANGUAGES

Remind used to support compile-time localization to other languages, but no longer does. All localization is now done at run-time.

RUN-TIME SUPPORT FOR OTHER LANGUAGES

Remind has run-time support for other languages, and compile-time support has been removed in favour of run-time support.

A number of system variables let you translate various phrases to other languages. These system variables are:

$Monday, $Tuesday, $Wednesday, $Thursday, $Friday, $Saturday, $Sunday
    Set each of these system variables to a string representing the corresponding day's name in your language. Strings must be valid UTF-8 strings.

$January, $February, $March, $April, $May, $June, $July, $August, $September, $October, $November, $December
    Set each of these system variables to a string representing the corresponding month's name in your language. Strings must be valid UTF-8 strings.

$Ago, $Am, $And, $At, $Hour, $Is, $Minute, $Now, $On, $Pm, $Today, $Tomorrow, $Was
    Set each of these system variables to the translation of the corresponding English word into your language. Note that $Am and $Pm should be the translations of "AM" and "PM" (morning and afternoon time indicators) respectively.

$Hplu, $Mplu
    Set these to the suffix to add to the word for "hour" and "minute" to make them plural. In English, both would be set to "s".

$Fromnow
    Set this to the translation of the English phrase "from now"

Note that if you set any of the language-related system variables, they should be set in a section of your script that always is evaluated. If you set them inside an IF statement, for example, results are unpredictable.

Note also that the Rem2PS back-end does not support the full range of UTF-8 characters. The TkRemind, rem2html and rem2pdf back-ends all do support the full UTF-8 range.

RUN-TIME MODIFICATION OF THE SUBSTITUTION FILTER

The system variables mentioned in the previous section are not typically sufficient to properly translate Remind's output to another language. Some languages have complicated rules for AM vs PM times and others have complex rules for making words plural. Remind therefore allows you to define a number of functions that modify the behavior of the substitution filter at run-time. The functions are:

subst_ampm(h)
    This function is passed a single integer, namely an hour from 0 to 23. It should return a string that indicates "AM" or "PM" or even finer gradations in some languages.

subst_ordinal(d)
    This function is passed a single integer, namely a day of the month from 1 to 31. It should return a string that is suffixed to the day number to turn it into an ordinal number. In English, for example, the function might return "st", "nd", "rd" or "th", depending on d.

subst_N(alt, date, time)
    This is actually a family of functions, where N is a letter or number. This function completely overrides the substitution sequence "%N". The three arguments are an integer alt which, if non-zero, indicates that the alternate-mode substitution sequence "%*N" was encountered; date which is the trigger date of the reminder and time which is the trigger time.

subst_Nx(alt, date, time)
    Again, this is a family of functions. It is similar to the subst_N family except it is only called if date is two or more days away from today(). This is useful if you don't want to override the "today" or "tomorrow" output for most substitution sequences.

Here's an example of how you might customize your substitution filter. Suppose you want to change the "%b" sequence to substitute "the day after tomorrow" for an event two days from now. You could do this:

    FSET subst_bx(a,d,t) iif(d==today()+2, "the day after tomorrow", \
                             "in " + (d-today()) + " days' time")
    REM [today()+3] ++3 MSG Event 1 is %b%
    REM [today()+2] ++3 MSG Event 2 is %b%
    REM [today()+1] ++3 MSG Event 3 is %b%
    REM [today()]   ++3 MSG Event 4 is %b%

The output of this script is:

    Event 1 is in 3 days' time
    Event 2 is the day after tomorrow
    Event 3 is tomorrow
    Event 4 is today

Note how Event 2's wording was changed from the normal "in 2 days' time", and note also that the "tomorrow" and "today" events used the normal substitution---subst_bx is not called for trigger days of today or tomorrow.

As a special case, if a subst_Nx or subst_N function returns the integer zero, then the normal substitution mechanism is used. Therefore, the previous example could have been written more simply as:

    FSET subst_bx(a,d,t) iif(d==today()+2, "the day after tomorrow", 0)

You can override substitution sequences that are not alphanumeric as follows:

    Override %: with subst_colon

    Override %! with subst_bang

    Override %? with subst_question

    Override %@ with subst_at

    Override %# with subst_hash

You can define your own substitution sequences in addition to the built-in ones as follows: If you define a function named subst_name(alt, date, time), then the sequence %{name} calls the function with alt set to 0 and date and time to the trigger date and time, respectively. The %{name} sequence is replaced with whatever the function returns. The sequence %*{name} is similar, but calls the function with alt set to 1.

If you use a %{name} sequence and the function subst_name is not defined or returns an error, then %{name} is replaced with the empty string.

Note that when Remind invokes any callback function for a substitution sequence, RUN will be disabled.

THE TRANSLATION TABLE

To assist with localizing reminder files, Remind maintains a table of translations. This is simple a lookup table that maps one string (the original string) to a new string (the translated string.) When Remind starts executing, the translation table is empty.

To add a message to the translation table, use the TRANSLATE command (which may be abbreviated to TRANS.) The TRANSLATE command must be followed by two quoted strings, separated from each other and from the command by whitespace. For example, a Dutch language file might contain something like this:

        TRANSLATE "New Moon" "Nieuwe maan"
        TRANSLATE "First Quarter" "Eerste kwartier"
        TRANSLATE "Full Moon" "Volle maan"
        TRANSLATE "Last Quarter" "Laatste kwartier"

To actually use the translation table, make use of the _ built-in function, as follows:

        REM NOQUEUE [moondatetime(0)] MSG [_("New Moon")] (%2)
        REM NOQUEUE [moondatetime(1)] MSG [_("First Quarter")] (%2)
        REM NOQUEUE [moondatetime(2)] MSG [_("Full Moon")] (%2)
        REM NOQUEUE [moondatetime(3)] MSG [_("Last Quarter")] (%2)

By using TRANSLATE and _ judiciously, you can make your reminder files easy to translate.

TRANSLATE has four additional forms: If it is followed by one quoted string instead of two, then Remind deletes the translation table entry for that string. If it is followed by the keyword DUMP, then Remind dumps all translation table entries to standard output. And if it is followed by CLEAR, then Remind deletes all of the translation table entries.

The fourth form, TRANSLATE GENERATE, dumps all of the strings that can be localized (as a series of TRANSLATE commands) to standard output. Strings that are already localized are output with their localization; strings that are not localized are output as:

        TRANSLATE "untranslated" ""

If you want to add a new language, you can obtain a skeleton translation
file by running:

        echo "TRANSLATE GENERATE" | remind -h - > /tmp/skeleton.rem

If you have an existing language file that is missing some translations, you can update it by running:

        (echo INCLUDE mylang.rem; echo TRANSLATE GENERATE) | \
            remind -h - > /tmp/mylang-update.rem

and then editing mylang-update.rem to add in the missing translations.

If you have some reminder scripts that use the _() built-in function or %(...) substitution sequence, you can generate a list of needed TRANSLATE commands by running:

        remind -q -n -dq myscript.rem 2>&1 | grep ^TRANSLATE | sort | uniq

Note that if you SET various translation-related system variables such as $Monday, $December, $Ago, etc, then Remind also makes a corresponding translation table entry automatically. This is done for all of the translation-related system variables except for $Hplu and $Mplu.

The converse applies too; creating a translation table for "December" automatically sets $December. And if you invoke TRANSLATE CLEAR, then all translation-related system variables are set to their default values as well.

The translation table always contains a special entry LANGID whose default value is en. Translators are encouraged to add a LANGID entry in their language files; the value should be the two-characters ISO 639 language code.

For example, if you write a translation file for the Dutch language, add this line:

        TRANSLATE "LANGID" "nl"

Scripts can use _("LANGID") to query the translation language that is in effect.

The _() function uses the following procedure to obtain the translation for a string:

    1   Look for an exact match. If found, return.

    2   If the original string had an upper-case letter, search for the all-lower-case equivalent. If found, make the first letter of the result upper-case and return.

    3   If the original string started with a lower-case letter, search for an equivalent whose first letter is upper-case and the rest lower-case. If found, make the first letter of the result lower-case and return.

    4   No translation was found. Return the original string.

LANGUAGE PACKS

Remind ships with a number of language packs, which are simply reminder scripts located in [$SysInclude]/lang. The currently-shipping language packs are:

da.rem (Danish), de.rem (German), es.rem (Spanish), fr.rem (French), is.rem (Icelandic), it.rem (Italian), nl.rem (Dutch), no.rem (Norwegian), pl.rem (Polish), pt.rem (Portuguese) and ro.rem (Romanian).

To use a language pack (in this example, de.rem), simply place this at the top of your reminders file:

    SYSINCLUDE lang/de.rem

If you want Remind to try to find the language pack appropriate for your locale settings, use:

    SYSINCLUDE lang/auto.rem

You are encouraged to study the language packs to see how to translate Remind into additional languages.

THE HEBREW CALENDAR

Remind has support for the Hebrew calendar, which is a luni-solar calendar. This allows you to create reminders for Jewish holidays, jahrzeits (anniversaries of deaths) and smachot (joyous occasions.)

THE HEBREW YEAR

The Hebrew year has 12 months, alternately 30 and 29 days long. The months are: Tishrey, Heshvan, Kislev, Tevet, Shvat, Adar, Nisan, Iyar, Sivan, Tamuz, Av and Elul. If you are in a UTF-8 locale, you can also use the UTF-8-encoded Hebrew spellings for the month names, namely:

תשרי, חשוון, כסלו, טבת, שבט, אדר, ניסן, אייר, סיון, תמוז, אב, אלול.

In a cycle of 19 years, there are 7 leap years, being years 3, 6, 8, 11, 14, 17 and 19 of the cycle. In a leap year, an extra month of 30 days is added before Adar. The two Adars are called Adar A and Adar B, or in Hebrew, 'אדר א and 'אדר ב.

Remind also permits the following alternative spellings for Hebrew month names:

Tishrey
    Can also be spelled Tishri or Tishrei

Heshvan
    Can also be spelled Cheshvan or Kheshvan

Shvat
    Can also be spelled Shevat

Tamuz
    Can also be spelled Tammuz

Adar A
    Can also be spelled Adar 1, Adar I, אדר א or אדר 1.

Adar B
    Can also be spelled Adar 2, Adar II, אדר ב or אדר 2.

Iyar
    Can also be spelled Iyyar.

For certain religious reasons, the year cannot start on a Sunday, Wednesday or Friday. To adjust for this, a day is taken off Kislev or added to Heshvan. Thus, a regular year can have from 353 to 355 days, and a leap year from 383 to 385.

When Kislev or Heshvan is short, it is called chaser, or lacking. When it is long, it is called shalem, or full.

The Jewish date changes at sunset. However, Remind will change the date at midnight, not sunset. So in the period between sunset and midnight, Remind will be a day earlier than the true Jewish date. This should not be much of a problem in practice.

The computations for the Jewish calendar were based on the program "hdate" written by Amos Shapir of the Hebrew University of Jerusalem, Israel. He also supplied the preceding explanation of the calendar.

HEBREW DATE FUNCTIONS

hebday(d_date)
    Returns the day of the Hebrew month corresponding to the date parameter. For example, 12 April 1993 corresponds to 21 Nisan 5753. Thus, hebday('1993/04/12') returns 21.

hebmon(d_date)
    Returns the name of the Hebrew month corresponding to date. For example, hebmon('1993/04/12') returns "Nisan".

ivritmon(d_date)
    Returns the name of the Hebrew month corresponding to date, in UTF-8-encoded Hebrew script. For example, ivritmon('1993/04/12') returns "ניסן".

hebyear(d_date)
    Returns the Hebrew year corresponding to date. For example, hebyear('1993/04/12') returns 5753.

hebdate(i_day, s_hebmon [,id_yrstart [,i_jahr [,i_aflag]]])
    The hebdate() function is the most complex of the Hebrew support functions. It can take from 2 to 5 arguments. It returns a DATE corresponding to the Hebrew date.

    The day parameter can range from 1 to 30, and specifies the day of the Hebrew month. The hebmon parameter is a string that must name one of the Hebrew months specified above. Note that the month must be spelled out in full, and use either the English transliteration shown previously, or the Hebrew spelling encoded in UTF-8. You can also specify "Adar A" and "Adar B." Month names are not case-sensitive.

    The yrstart parameter can either be a DATE or an INT. If it is a DATE, then the hebdate() scans for the first Hebrew date on or after that date. For example:

    		hebdate(15, "Nisan", '1990/01/01')

    returns 1990/03/30, because that is the first occurrence of 15 Nisan on or after 1 January 1990.

    If yrstart is an INT, it is interpreted as a Hebrew year. Thus:

    		hebdate(22, "Kislev", 5756)

    returns 1995/12/15, because that date corresponds to 22 Kislev, 5756. Note that none of the Hebrew date functions will work with dates outside Remind's normal range for dates.

    If yrstart is not supplied, it defaults to today().

    The jahr modifies the behaviour of hebdate() as follows:

    If jahr is 0 (the default), then hebdate() keeps scanning until it finds a date that exactly satisfies the other parameters. For example:

    		hebdate(30, "Adar A", 1993/01/01)

    returns 1995/03/02, corresponding to 30 Adar A, 5755, because that is the next occurrence of 30 Adar A after 1 January, 1993. This behaviour is appropriate for Purim Katan, which only appears in leap years.

    If jahr is 1, then the date is modified as follows:

    o   30 Heshvan is converted to 1 Kislev in years when Heshvan is chaser

    o   30 Kislev is converted to 1 Tevet in years when Kislev is chaser

    o   30 Adar A is converted to 1 Nisan in non-leapyears

    o   Other dates in Adar A are moved to the corresponding day in Adar in non-leapyears

    This behaviour is appropriate for smachot (joyous occasions) and for some jahrzeits - see "JAHRZEITS."

    if jahr is 2, then the date is modified as follows:

    o   30 Kislev and 30 Heshvan are converted to 29 Kislev and 29 Heshvan, respectively, if the month is chaser

    o   30 Adar A is converted to 30 Shvat in non-leapyears

    o   Other dates in Adar A are moved to the corresponding day in Adar in non-leapyears

    if jahr is not 0, 1, or 2, it is interpreted as a Hebrew year, and the behaviour is calculated as described in the next section, "JAHRZEITS."

    The aflag parameter modifies the behaviour of the function for dates in Adar during leap years. The aflag is only used if yrstart is a DATE type.

    The aflag only affects date calculations if hebmon is specified as "Adar". In leap years, the following algorithm is followed:

    o   If aflag is 0, then the date is triggered in Adar B. This is the default.

    o   If aflag is 1, then the date is triggered in Adar A. This may be appropriate for jahrzeits in the Ashkenazi tradition; consult a rabbi.

    o   If aflag is 2, then the date is triggered in both Adar A and Adar B of a leap year. Some Ashkenazim perform jahrzeit in both Adar A and Adar B.

JAHRZEITS

A jahrzeit is a yearly commemoration of someone's death. It normally takes place on the anniversary of the death, but may be delayed if burial is delayed - consult a rabbi for more information.

In addition, because some months change length, it is not obvious which day the anniversary of a death is. The following rules are used:

o   If the death occurred on 30 Heshvan, and Heshvan in the year after the death is chaser, then the jahrzeit is observed on 29 Heshvan in years when Heshvan is chaser. Otherwise, the jahrzeit is observed on 1 Kislev when Heshvan is chaser.

o   If the death occurred on 30 Kislev, and Kislev in the year after the death is chaser, then the jahrzeit is observed on 29 Kislev in years when Kislev is chaser. Otherwise, the jahrzeit is observed on 1 Tevet when Kislev is chaser.

o   If the death occurred on 1-29 Adar A, it is observed on 1-29 Adar in non-leapyears.

o   If the death occurred on 30 Adar A, it is observed on 30 Shvat in a non-leapyear.

Specifying a Hebrew year for the jahr parameter causes the correct behaviour to be selected for a death in that year. You may also have to specify aflag, depending on your tradition.

The jahrzeit information was supplied by Frank Yellin, who quoted "The Comprehensive Hebrew Calendar" by Arthur Spier, and "Calendrical Calculations" by E. M. Reingold and Nachum Dershowitz.

OUT-OF-BAND REMINDERS

The SPECIAL keyword is used to transmit "out-of-band" information to Remind backends, such as tkremind or Rem2PS. They are used only when piping data from a remind -p line. (Note that the COLOR special is an exception; it works similarly to MSG when the -p option is not supplied.)

The various SPECIALs recognized are particular for each backend; however, there are four SPECIALs that all backends should attempt to support. They are currently supported by Rem2PS, tkremind and rem2html.

The SHADE special replaces the psshade() function. Use it like this:

	REM Sat Sun SPECIAL SHADE 128
	REM Mon SPECIAL SHADE 255 0 0

The SHADE keyword is followed by either one or three numbers, from 0 to 255. If one number is supplied, it is interpreted as a grey-scale value from black (0) to white (255). If three numbers are supplied, they are interpreted as RGB components from minimum (0) to maximum (255). The example above shades weekends a fairly dark grey and makes Mondays a fully-saturated red. (These shadings appear in calendars produced by Rem2PS, tkremind and rem2html.)

The MOON special replaces the psmoon() function. Use it like this:

	REM [moondate(0)] SPECIAL MOON 0
	REM [moondate(1)] SPECIAL MOON 1
	REM [moondate(2)] SPECIAL MOON 2
	REM [moondate(3)] SPECIAL MOON 3

These draw little moons on the various calendars. The complete syntax of the MOON special is as follows:

	... SPECIAL MOON phase moonsize fontsize msg

Phase is a number from 0 to 3, with 0 representing a new moon, 1 the first quarter, 2 a full moon and 3 the last quarter.

moonsize is the diameter in PostScript units of the moon to draw. If omitted or supplied as -1, the backend chooses an appropriate size.

fontsize is the font size in PostScript units of the msg

Msg is additional text that is placed near the moon glyph.

Note that only the Rem2PS backend supports moonsize and fontsize; the other backends use fixed sizes.

The COLOR special lets you place colored reminders in the calendar. Use it like this:

	REM ... SPECIAL COLOR 255 0 0 This is a bright red reminder
	REM ... SPECIAL COLOR 0 128 0 This is a dark green reminder

You can spell COLOR either the American way ("COLOR") or the British way ("COLOUR"). This manual will use the American way. Immediately following COLOR should be three decimal numbers ranging from 0 to 255 specifying red, green and blue intensities, respectively. The rest of the line is the text to put in the calendar.

The COLOR special is "doubly special", because in agenda mode, remind treats a COLOR special just like a MSG-type reminder. Also, if you invoke Remind with -@[n], then it approximates SPECIAL COLOR reminders on your terminal.

See also the documentation of the $DefaultColor system variable in the section "SYSTEM VARIABLES".

The WEEK special lets you place annotations such as the week number in the calendar. For example, this would number each Monday with the ISO 8601 week number. The week number is shown like this: "(Wn)" in this example, but you can put whatever text you like after the WEEK keyword.

	REM Monday SPECIAL WEEK (W[weekno()])

MISCELLANEOUS

COMMAND AND KEYWORD ABBREVIATIONS

The following tokens can be abbreviated:

o   CLEAR-OMIT-CONTEXT --> CLEAR

o   PUSH-OMIT-CONTEXT --> PUSH

o   POP-OMIT-CONTEXT --> POP

o   DUMPVARS --> DUMP

o   BANNER --> BAN

o   INCLUDE --> INC

o   MAYBE-UNCOMPUTABLE --> MAYBE

o   SCANFROM --> SCAN

NIFTY EXAMPLES

This section is a sampling of what you can do with Remind.

	REM 5 Feb 1991 AT 14:00 +45 *30 \
	RUN mail -s "Meeting at %2" $LOGNAME </dev/null &

On 5 February, 1991, this reminder will mail you reminders of a 2:00pm meeting at 1:15, 1:45 and 2:00. The subject of the mail message will be "Meeting at 2:00pm" and the body of the message will be blank.

	REM AT 17:00 RUN echo "5:00pm - GO HOME!" | xless -g +0+0 &

This reminder will pop up an xless window at 5:00pm every day. The xless window will contain the line "5:00pm - GO HOME!"

	REM AT 23:59 RUN (sleep 120; remind -a [filename()]) &

This reminder will run at one minute to midnight. It will cause a new Remind process to start at one minute past midnight. This allows you to have a continuous reminder service so you can work through the night and still get timed reminders for early in the morning. Note that this trick is no longer necessary, providing you run Remind in daemon mode.

	remind -c12 /dev/null Jan 1993

This invocation of Remind will cause it to print a calendar for 1993, with all entries left blank.

	REM CAL [trigdate()-date(year(trigdate()), 1, 1)+1]

This example puts an entry in each box of a calendar showing the number (1-365 or 366) of the day of the year.

	REM Tue 2 Nov SATISFY (year(trigdate())%4) == 0
	IF trigvalid()
		REM [trigdate()] ++5 MSG \
		U.S. Presidential Election!!
	ENDIF

This example warns you 5 days ahead of each American presidential election. The first REM command calculates the first Tuesday after the first Monday in November. (This is equivalent to the first Tuesday on or after 2 November.) The SATISFY clause ensures that the trigger date is issued only in election years, which are multiples of 4. The second REM command actually issues the reminder.

DETAILS ABOUT TRIGGER COMPUTATION

Here is a conceptual description of how triggers are calculated. Note that Remind actually uses a much more efficient procedure, but the results are the same as if the conceptual procedure had been followed.

Remind starts from the current date (that is, the value of today()) and scans forward, examining each day one at a time until it finds a date that satisfies the trigger, or can prove that no such dates (on or later than today()) exist.

If Remind is executing a SATISFY-type reminder, it evaluates the expression with trigdate() set to the date found above. If the expression evaluates to zero or the null string, Remind continues the scanning procedure described above, starting with the day after the trigger found above.

The SCANFROM clause (having a syntax similar to UNTIL) can modify the search strategy used. In this case, Remind begins the scanning procedure at scan_date, which is the date specified in the SCANFROM clause. For example:

	REM Mon 1 SCANFROM 17 Jan 1992 MSG Foo

The example above will always have a trigger date of Monday, 3 February 1992. That is because Remind starts scanning from 17 January 1992, and stops scanning as soon as it hits a date that satisfies "Mon 1."

The main use of SCANFROM is in situations where you want to calculate the positions of floating holidays. Consider the Labour Day example shown much earlier. Labour Day is the first Monday in September. It can move over a range of 7 days. Consider the following sequence:

	REM Mon 1 Sept SCANFROM [today()-7] ADDOMIT MSG Labour Day
	REM Mon AFTER MSG Hello

The SCANFROM clause makes sure that Remind begins scanning from 7 days before the current date. This ensures that Labour Day for the current year will continue to be triggered until 7 days after it has occurred. This allows you to safely use the AFTER keyword as shown.

As a special case, you can simply use a negative number after SCANFROM; a negative number -N is interpreted as N days before today. Thus, the previous example could also be written like this:

	REM Mon 1 Sept SCANFROM -7 ADDOMIT MSG Labour Day
	REM Mon AFTER MSG Hello

A SCANFROM that specifies a full date is called an absolute SCANFROM and a SCANFROM that specifies a negative number is called a relative SCANFROM.

In general, use SCANFROM as shown for safe movable OMITs. The amount you should scan back by (7 days in the example above) depends on the number of possible consecutive OMITted days that may occur, and on the range of the movable holiday. Generally, a value of 7 is safe.

The FROM clause operates almost like the counterpoint to UNTIL. It prevents the reminder from triggering before the FROM date. For example, the following reminder:

	REM Mon Thu FROM 23 Jul 2007 UNTIL 2 Aug 2007 MSG Test

will trigger on Mondays and Thursdays between 23 July 2007 and 2 August 2007 inclusive.

FROM is really just syntactic sugar; you could implement the reminder above as follows:

	REM Mon Thu SCANFROM [max(today(), '2007-07-23')] \
            UNTIL 2 Aug 2007 MSG Test

but that's a lot harder to read. Internally, Remind treats FROM exactly as illustrated using SCANFROM. For that reason, you cannot use both FROM and SCANFROM.

Note that if you use one REM command to calculate a trigger date, perform date calculations (addition or subtraction, for example) and then use the modified date in a subsequent REM command, the results may not be what you intended. This is because you have circumvented the normal scanning mechanism. You should try to write REM commands that compute trigger dates that can be used unmodified in subsequent REM commands. The file "defs.rem" that comes with the Remind distribution contains examples.

DETAILS ABOUT TRIGVALID()

The trigvalid() function returns 1 if Remind could find a trigger date for the previous REM or IFTRIG command. More specifically, it returns 1 if Remind finds a date not before the starting date of the scanning that satisfies the trigger. In addition, there is one special case in which trigvalid() returns 1 and trigdate() returns a meaningful result:

If the REM or IFTRIG command did not contain an UNTIL or SATISFY clause, and contained all of the day, month and year components, then Remind will correctly compute a trigger date, even if it happens to be before the start of scanning. Note that this behaviour is not true for versions of Remind prior to 03.00.01.

FILES

The traditional location of your reminders file or directory is:

        $HOME/.reminders

where $HOME is your home directory.

Remind ships with some preinstalled files for holidays and language packs. These are located in the following directory:

        /usr/local/share/remind/

Do not hard-code the above directory in your reminder files. Instead, use the value of the $SysInclude system variable.

AUTHOR

Dianne Skoll <dianne@skoll.ca> wrote Remind. The moon phase code was copied largely unmodified from "moontool" by John Walker. The moonrise/moonset code comes from https://github.com/signetica/MoonRise by Stephen R. Schmitt and Cyrus Rahman. The sunrise and sunset functions use ideas from programs by Michael Schwartz and Marc T. Kaufman. The Hebrew calendar support was taken from "hdate" by Amos Shapir. The supported languages and their translators are listed below. Languages marked "complete" support error messages in that language; all others only support the substitution filter mechanism and month/day names.

German -- Wolfgang Thronicke

Dutch -- Willem Kasdorp and Erik-Jan Vens

Finnish -- Mikko Silvonen (complete)

French -- Laurent Duperval (complete)

Norwegian -- Trygve Randen

Danish -- Mogens Lynnerup

Polish -- Jerzy Sobczyk (complete)

Brazilian Portuguese -- Marco Paganini (complete)

Italian -- Valerio Aimale

Romanian -- Liviu Daia

Spanish -- Rafa Couto

Icelandic -- Björn Davíðsson

BUGS

If you find a bug in Remind, please report it to: dianne@skoll.ca

There's no good reason why read-only system variables are not implemented as functions, or why functions like version(), etc. are not implemented as read-only system variables.

Hebrew dates in Remind change at midnight instead of sunset.

Remind has some built-in limits (for example, number of global OMITs.)

BIBLIOGRAPHY

Nachum Dershowitz and Edward M. Reingold, "Calendrical Calculations", Software-Practice and Experience, Vol. 20(9), Sept. 1990, pp 899-928.

L. E. Doggett, Almanac for computers for the year 1978, Nautical Almanac Office, USNO.

Richard Siegel and Michael and Sharon Strassfeld, The First Jewish Catalog, Jewish Publication Society of America.

Jean Meeus, Astronomical Algorithms, Second Edition, Willmann-Bell, Inc.

HOME PAGE
https://dianne.skoll.ca/projects/remind/

MAILING LIST
https://dianne.skoll.ca/mailman/listinfo/remind-fans

SEE ALSO

rem(1), rem2ps(1), rem2pdf(1), tkremind(1), rem2html(1)