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CUT(1P) POSIX Programmer's Manual CUT(1P)
PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (con-
sult 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 IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guide-
lines.
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 represents 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 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-
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 char-
acter, 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 delim-
iters 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 IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for the precedence of international-
ization 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 stan-
dard 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 (mod-
ulo <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 bound-
aries. 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 remain-
der 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 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>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 continu-
ing 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 deliberately left unspecified in favor of global wording in 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
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, Copy-
right (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.open-
group.org/unix/online.html .
IEEE/The Open Group 2003 CUT(1P)
