CUT(P) POSIX Programmer's Manual CUT(P)NAMEcut - cut out selected fields of each line of a file
SYNOPSIScut-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
IEEE Std 1003.1-2001, 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 ( low- high), which
represents all fields from the first number to the second number. The
second is a positive number preceded by a hyphen (- high), which repre‐
sents all fields from field number 1 to that number. The third is a
positive number followed by a hyphen ( 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 speci‐
fied. 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-separated numbers)
shall be modified as follows:
* If the byte selected by low is not the first byte of a char‐
acter, 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 ele‐
ment 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 speci‐
fied, 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
IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
ables 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
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 charac‐
ter 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 IEEE Std 1003.1-2001 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>s in determin‐
ing 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>s or <tab>s 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
IEEE Std 1003.1-2001, 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 delib‐
erately left unspecified in favor of global wording in Utility Descrip‐
tion 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 out‐
put.
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 speci‐
fied, 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, char‐
acters, 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
grep , paste , Parameters and Variables
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 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 .
IEEE/The Open Group 2003 CUT(P)
