CUT(1)                     POSIX Programmer's Manual                    CUT(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
       cut -- cut out selected fields of each line of a file

SYNOPSIS
       cut -b list [[-n]] [[file...]]

       cut -c list [[file...]]

       cut -f list [[-d delim]] [[-s]] [[file...]]

DESCRIPTION
       The cut utility shall cut out bytes (-b option), characters (-c
       option), or character-delimited fields (-f option) from each line in
       one or more files, concatenate them, and write them to standard output.

OPTIONS
       The cut utility shall conform to the Base Definitions volume of
       POSIX.1-2017, Section 12.2, Utility Syntax Guidelines.

       The application shall ensure that the option-argument list (see options
       -b, -c, and -f below) is a <comma>-separated list or <blank>-separated
       list of positive numbers and ranges. Ranges can be in three forms. The
       first is two positive numbers separated by a <hyphen-minus> (low-high),
       which represents all fields from the first number to the second number.
       The second is a positive number preceded by a <hyphen-minus> (-high),
       which represents all fields from field number 1 to that number. The
       third is a positive number followed by a <hyphen-minus> (low-), which
       represents that number to the last field, inclusive. The elements in
       list can be repeated, can overlap, and can be specified in any order,
       but the bytes, characters, or fields selected shall be written in the
       order of the input data. If an element appears in the selection list
       more than once, it shall be written exactly once.

       The following options shall be supported:

       -b list   Cut based on a list of bytes. Each selected byte shall be
                 output unless the -n option is also specified. It shall not
                 be an error to select bytes not present in the input line.

       -c list   Cut based on a list of characters. Each selected character
                 shall be output. It shall not be an error to select
                 characters not present in the input line.

       -d delim  Set the field delimiter to the character delim.  The default
                 is the <tab>.

       -f list   Cut based on a list of fields, assumed to be separated in the
                 file by a delimiter character (see -d).  Each selected field
                 shall be output. Output fields shall be separated by a single
                 occurrence of the field delimiter character. Lines with no
                 field delimiters shall be passed through intact, unless -s is
                 specified. It shall not be an error to select fields not
                 present in the input line.

       -n        Do not split characters. When specified with the -b option,
                 each element in list of the form low-high (<hyphen-
                 minus>-separated numbers) shall be modified as follows:

                  *  If the byte selected by low is not the first byte of a
                     character, low shall be decremented to select the first
                     byte of the character originally selected by low.  If the
                     byte selected by high is not the last byte of a
                     character, high shall be decremented to select the last
                     byte of the character prior to the character originally
                     selected by high, or zero if there is no prior character.
                     If the resulting range element has high equal to zero or
                     low greater than high, the list element shall be dropped
                     from list for that input line without causing an error.

                 Each element in list of the form low- shall be treated as
                 above with high set to the number of bytes in the current
                 line, not including the terminating <newline>.  Each element
                 in list of the form -high shall be treated as above with low
                 set to 1. Each element in list of the form num (a single
                 number) shall be treated as above with low set to num and
                 high set to num.

       -s        Suppress lines with no delimiter characters, when used with
                 the -f option. Unless specified, lines with no delimiters
                 shall be passed through untouched.

OPERANDS
       The following operand shall be supported:

       file      A pathname of an input file. If no file operands are
                 specified, or if a file operand is ''--'', the standard input
                 shall be used.

STDIN
       The standard input shall be used only if no file operands are
       specified, or if a file operand is ''--''.  See the INPUT FILES section.

INPUT FILES
       The input files shall be text files, except that line lengths shall be
       unlimited.

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

       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.

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

ASYNCHRONOUS EVENTS
       Default.

STDOUT
       The cut utility output shall be a concatenation of the selected bytes,
       characters, or fields (one of the following):


           "%s\n", <concatenation of bytes>

           "%s\n", <concatenation of characters>

           "%s\n", <concatenation of fields and field delimiters>

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

OUTPUT FILES
       None.

EXTENDED DESCRIPTION
       None.

EXIT STATUS
       The following exit values shall be returned:

        0    All input files were output successfully.

       >0    An error occurred.

CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       The cut and fold utilities can be used to create text files out of
       files with arbitrary line lengths. The cut utility should be used when
       the number of lines (or records) needs to remain constant. The fold
       utility should be used when the contents of long lines need to be kept
       contiguous.

       Earlier versions of the cut utility worked in an environment where
       bytes and characters were considered equivalent (modulo <backspace> and
       <tab> processing in some implementations). In the extended world of
       multi-byte characters, the new -b option has been added. The -n option
       (used with -b) allows it to be used to act on bytes rounded to
       character boundaries.  The algorithm specified for -n guarantees that:


           cut -b 1-500 -n file > file1
           cut -b 501- -n file > file2

       ends up with all the characters in file appearing exactly once in file1
       or file2.  (There is, however, a <newline> in both file1 and file2 for
       each <newline> in file.)

EXAMPLES
       Examples of the option qualifier list:

       1,4,7   Select the first, fourth, and seventh bytes, characters, or
               fields and field delimiters.

       1-3,8   Equivalent to 1,2,3,8.

       -5,10   Equivalent to 1,2,3,4,5,10.

       3-      Equivalent to third to last, inclusive.

       The low-high forms are not always equivalent when used with -b and -n
       and multi-byte characters; see the description of -n.

       The following command:


           cut -d : -f 1,6 /etc/passwd

       reads the System V password file (user database) and produces lines of
       the form:


           <user ID>:<home directory>

       Most utilities in this volume of POSIX.1-2017 work on text files. The
       cut utility can be used to turn files with arbitrary line lengths into
       a set of text files containing the same data. The paste utility can be
       used to create (or recreate) files with arbitrary line lengths. For
       example, if file contains long lines:


           cut -b 1-500 -n file > file1
           cut -b 501- -n file > file2

       creates file1 (a text file) with lines no longer than 500 bytes (plus
       the <newline>) and file2 that contains the remainder of the data from
       file.  (Note that file2 is not a text file if there are lines in file
       that are longer than 500 + {LINE_MAX} bytes.) The original file can be
       recreated from file1 and file2 using the command:


           paste -d "\0" file1 file2 > file

RATIONALE
       Some historical implementations do not count <backspace> characters in
       determining character counts with the -c option. This may be useful for
       using cut for processing nroff output. It was deliberately decided not
       to have the -c option treat either <backspace> or <tab> characters in
       any special fashion. The fold utility does treat these characters
       specially.

       Unlike other utilities, some historical implementations of cut exit
       after not finding an input file, rather than continuing to process the
       remaining file operands. This behavior is prohibited by this volume of
       POSIX.1-2017, where only the exit status is affected by this problem.

       The behavior of cut when provided with either mutually-exclusive
       options or options that do not work logically together has been
       deliberately left unspecified in favor of global wording in Section
       1.4, Utility Description Defaults.

       The OPTIONS section was changed in response to IEEE PASC Interpretation
       1003.2 #149. The change represents historical practice on all known
       systems. The original standard was ambiguous on the nature of the
       output.

       The list option-arguments are historically used to select the portions
       of the line to be written, but do not affect the order of the data. For
       example:


           echo abcdefghi | cut -c6,2,4-7,1

       yields "abdefg".

       A proposal to enhance cut with the following option:

       -o    Preserve the selected field order. When this option is specified,
             each byte, character, or field (or ranges of such) shall be
             written in the order specified by the list option-argument, even
             if this requires multiple outputs of the same bytes, characters,
             or fields.

       was rejected because this type of enhancement is outside the scope of
       the IEEE P1003.2b draft standard.

FUTURE DIRECTIONS
       None.

SEE ALSO
       Section 2.5, Parameters and Variables, fold, grep, paste

       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                               CUT(1)
