cut (Unix)

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In computing, cut is a Unix command line utility 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. It first appeared in AT&T System III UNIX in 1982.[1]

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.

Examples[edit]

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:teta: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

This gives the output:

: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

This gives the output:

quux
five:six:seven
epsilon:zeta:eta:teta: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 specified 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

This gives the output:

foo:bar:baz:qux:quux
one:two:three:four:five:six:seven
alpha:beta:gamma:delta:epsilon:zeta:eta:teta: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
$ cut -d "." -f2 $line

This gives the output:

process
processid

Syntax[edit]

 cut [-b] [-c] [-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.

See also[edit]

References[edit]

External links[edit]