DELTA(1)                   POSIX Programmer's Manual                  DELTA(1)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NAME
       delta -- make a delta (change) to an SCCS file (DEVELOPMENT)

SYNOPSIS
       delta [[-nps]] [[-g list]] [[-m mrlist]] [[-r SID]] [[-y[[comment]]]] file...

DESCRIPTION
       The delta utility shall be used to permanently introduce into the named
       SCCS files changes that were made to the files retrieved by get (called
       the g-files, or generated files).

OPTIONS
       The delta utility shall conform to the Base Definitions volume of
       POSIX.1-2017, Section 12.2, Utility Syntax Guidelines, except that the
       -y option has an optional option-argument. This optional option-
       argument shall not be presented as a separate argument.

       The following options shall be supported:

       -r SID    Uniquely identify which delta is to be made to the SCCS file.
                 The use of this option shall be necessary only if two or more
                 outstanding get commands for editing (get -e) on the same
                 SCCS file were done by the same person (login name). The SID
                 value specified with the -r option can be either the SID
                 specified on the get command line or the SID to be made as
                 reported by the get utility; see get.

       -s        Suppress the report to standard output of the activity
                 associated with each file.  See the STDOUT section.

       -n        Specify retention of the edited g-file (normally removed at
                 completion of delta processing).

       -g list   Specify a list (see get for the definition of list) of deltas
                 that shall be ignored when the file is accessed at the change
                 level (SID) created by this delta.

       -m mrlist Specify a modification request (MR) number that the
                 application shall supply as the reason for creating the new
                 delta. This shall be used if the SCCS file has the vv flag
                 set; see admin.

                 If -m is not used and ''--'' is not specified as a file
                 argument, and the standard input is a terminal, the prompt
                 described in the STDOUT section shall be written to standard
                 output before the standard input is read; if the standard
                 input is not a terminal, no prompt shall be issued.

                 MRs in a list shall be separated by <blank> characters or
                 escaped <newline> characters. An unescaped <newline> shall
                 terminate the MR list. The escape character is <backslash>.

                 If the vv flag has a value, it shall be taken to be the name
                 of a program which validates the correctness of the MR
                 numbers. If a non-zero exit status is returned from the MR
                 number validation program, the delta utility shall terminate.
                 (It is assumed that the MR numbers were not all valid.)

       -y[comment]]
                 Describe the reason for making the delta. The comment shall
                 be an arbitrary group of lines that would meet the definition
                 of a text file. Implementations shall support comments from
                 zero to 512 bytes and may support longer values. A null
                 string (specified as either -y, -y"", or in response to a
                 prompt for a comment) shall be considered a valid comment.

                 If -y is not specified and ''--'' is not specified as a file
                 argument, and the standard input is a terminal, the prompt
                 described in the STDOUT section shall be written to standard
                 output before the standard input is read; if the standard
                 input is not a terminal, no prompt shall be issued. An
                 unescaped <newline> shall terminate the comment text. The
                 escape character is <backslash>.

                 The -y option shall be required if the file operand is
                 specified as ''--''.

       -p        Write (to standard output) the SCCS file differences before
                 and after the delta is applied in diff format; see diff.

OPERANDS
       The following operand shall be supported:

       file      A pathname of an existing SCCS file or a directory. If file
                 is a directory, the delta utility shall behave as though each
                 file in the directory were specified as a named file, except
                 that non-SCCS files (last component of the pathname does not
                 begin with ss..)  and unreadable files shall be silently
                 ignored.

                 If exactly one file operand appears, and it is ''--'', the
                 standard input shall be read; each line of the standard input
                 shall be taken to be the name of an SCCS file to be
                 processed. Non-SCCS files and unreadable files shall be
                 silently ignored.

STDIN
       The standard input shall be a text file used only in the following
       cases:

        *  To read an mrlist or a comment (see the -m and -y options).

        *  A file operand shall be specified as ''--''.  In this case, the -y
           option must be used to specify the comment, and if the SCCS file
           has the vv flag set, the -m option must also be used to specify the
           MR list.

INPUT FILES
       Input files shall be text files whose data is to be included in the
       SCCS files. If the first character of any line of an input file is
       <SOH> in the POSIX locale, the results are unspecified. If this file
       contains more than 99999 lines, the number of lines recorded in the
       header for this file shall be 99999 for this delta.

ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of
       delta:

       LANG      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base Definitions
                 volume of POSIX.1-2017, Section 8.2, Internationalization
                 Variables for the precedence of internationalization
                 variables used to determine the values of locale categories.)

       LC__ALL    If set to a non-empty string value, override the values of
                 all the other internationalization variables.

       LC__CTYPE  Determine the locale for the interpretation of sequences of
                 bytes of text data as characters (for example, single-byte as
                 opposed to multi-byte characters in arguments and input
                 files).

       LC__MESSAGES
                 Determine the locale that should be used to affect the format
                 and contents of diagnostic messages written to standard
                 error, and informative messages written to standard output.

       NLSPATH   Determine the location of message catalogs for the processing
                 of LC__MESSAGES.

       TZ        Determine the timezone in which the time and date are written
                 in the SCCS file. If the TZ variable is unset or NULL, an
                 unspecified system default timezone is used.

ASYNCHRONOUS EVENTS
       If SIGINT is caught, temporary files shall be cleaned up and delta
       shall exit with a non-zero exit code. The standard action shall be
       taken for all other signals; see Section 1.4, Utility Description
       Defaults.

STDOUT
       The standard output shall be used only for the following messages in
       the POSIX locale:

        *  Prompts (see the -m and -y options) in the following formats:


               "MRs? "

               "comments? "

           The MR prompt, if written, shall always precede the comments
           prompt.

        *  A report of each file's activities (unless the -s option is
           specified) in the following format:


               "%s\n%d inserted\n%d deleted\n%d unchanged\n", <New SID>,
                   <number of lines inserted>, <number of lines deleted>,
                   <number of lines unchanged>

STDERR
       The standard error shall be used only for diagnostic messages.

OUTPUT FILES
       Any SCCS files updated shall be files of an unspecified format.

EXTENDED DESCRIPTION
   System Date and Time
       When a delta is added to an SCCS file, the system date and time shall
       be recorded for the new delta. If a get is performed using an SCCS file
       with a date recorded apparently in the future, the behavior is
       unspecified.

EXIT STATUS
       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.

CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       Problems can arise if the system date and time have been modified (for
       example, put forward and then back again, or unsynchronized clocks
       across a network) and can also arise when different values of the TZ
       environment variable are used.

       Problems of a similar nature can also arise for the operation of the
       get utility, which records the date and time in the file body.

EXAMPLES
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       Section 1.4, Utility Description Defaults, admin, diff, get, prs, rmdel

       The Base Definitions volume of POSIX.1-2017, Chapter _8, Environment
       Variables, Section 12.2, Utility Syntax Guidelines

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  In the event of any discrepancy between this version and the
       original IEEE and The Open Group Standard, the original IEEE and The
       Open Group Standard is the referee document. The original Standard can
       be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                             DELTA(1)
