cut (Unix)
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
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
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
References
External links
- Softpanorama cut page.
- – Commands & Utilities Reference, The Single UNIX® Specification, Issue 7 from The Open Group
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