Ubuntu Manpage: This manual page is part of the POSIX Programmer's Manual. The Linux implementation of

Provided by: manpages-posix_2017a-2_all

PROLOG

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

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:

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.

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 .