Cut (Unix)

cut
Original author(s)	AT&T Bell Laboratories
Developer(s)	Various open-source and commercial developers
Initial release	February 1985; 39 years ago
Operating system	Unix, Unix-like, IBM i
Platform	Cross-platform
Type	Command
License	coreutils: GPLv3+

In computing, cut is a command line utility on Unix and Unix-like operating systems which is used to extract sections from each line of input — usually from a file. It is currently part of the GNU coreutils package and the BSD Base System.

Extraction of line segments can typically be done by bytes (-b), characters (-c), or fields (-f) separated by a delimiter (-d — the tab character by default). A range must be provided in each case which consists of one of N, N-M, N- (N to the end of the line), or -M (beginning of the line to M), where N and M are counted from 1 (there is no zeroth value). Since version 6, an error is thrown if you include a zeroth value. Prior to this the value was ignored and assumed to be 1.

History

The original Bell Labs version was written by Gottfried W. R. Luderer.^[1]^[2] cut is part of the X/Open Portability Guide since issue 2 of 1987. It was inherited into the first version of POSIX.1 and the Single Unix Specification.^[3] It first appeared in AT&T System III UNIX in 1982.^[4]

The version of cut bundled in GNU coreutils was written by David M. Ihnat, David MacKenzie, and Jim Meyering.^[5] The command is available as a separate package for Microsoft Windows as part of the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities.^[6] The cut command has also been ported to the IBM i operating system.^[7]

Examples

Assuming a file named "file" containing the lines:

foo:bar:baz:qux:quux
one:two:three:four:five:six:seven
alpha:beta:gamma:delta:epsilon:zeta:eta:theta:iota:kappa:lambda:mu
the quick brown fox jumps over the lazy dog

To output the fourth through tenth characters of each line:

$ cut -c 4-10 file
:bar:ba
:two:th
ha:beta
 quick

To output the fifth field through the end of the line of each line using the colon character as the field delimiter:

$ cut -d ":" -f 5- file
quux
five:six:seven
epsilon:zeta:eta:theta:iota:kappa:lambda:mu
the quick brown fox jumps over the lazy dog

(note that because the colon character is not found in the last line the entire line is shown)

Option -d specifies a single character delimiter (in the example above it is a colon) which serves as field separator. Option -f which specifies range of fields included in the output (here fields range from five till the end). Option -d presupposes usage of option -f.

To output the third field of each line using space as the field delimiter:

$ cut -d " " -f 3 file
foo:bar:baz:qux:quux
one:two:three:four:five:six:seven
alpha:beta:gamma:delta:epsilon:zeta:eta:theta:iota:kappa:lambda:mu
brown

(Note that because the space character is not found in the first three lines these entire lines are shown.)

To separate two words having any delimiter:

$ line=process.processid
$ cut -d "." -f1 <<< $line
process
$ cut -d "." -f2 <<< $line
processid

Syntax

cut [-b list] [-c list] [-f list] [-n] [-d delim] [-s] [file]

Flags which may be used include:

-b: Bytes; a list following -b specifies a range of bytes which will be returned, e.g. cut -b1-66 would return the first 66 bytes of a line. NB If used in conjunction with -n, no multi-byte characters will be split. NNB. -b will only work on input lines of less than 1023 bytes
-c: Characters; a list following -c specifies a range of characters which will be returned, e.g. cut -c1-66 would return the first 66 characters of a line
-f: Specifies a field list, separated by a delimiter
list: A comma separated or blank separated list of integer denoted fields, incrementally ordered. The - indicator may be supplied as shorthand to allow inclusion of ranges of fields e.g. 4-6 for ranges 4–6 or 5- as shorthand for field 5 to the end, etc.
-n: Used in combination with -b suppresses splits of multi-byte characters
-d: Delimiter; the character immediately following the -d option is the field delimiter for use in conjunction with the -f option; the default delimiter is tab. Space and other characters with special meanings within the context of the shell in use must be enquoted or escaped as necessary.
-s: Bypasses lines which contain no field delimiters when -f is specified, unless otherwise indicated.
file: The file (and accompanying path if necessary) to process as input. If no file is specified then standard input will be used.