What is the cut command in UNIX?
The cut command in UNIX is a command line utility for cutting sections from each line of files and writing the result to standard output. It can be used to cut parts of a line by byte position, character and delimiter. It can also be used to cut data from file formats like CSV.
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How to cut by byte position
To cut out a section of a line by specifying a byte position use the -b option.
echo 'baz' | cut -b 2
a
echo 'baz' | cut -b 1-2
ba
echo 'baz' | cut -b 1,3
bz
How to cut by character
To cut by character use the -c option. This selects the characters given to the -c option. This can be a list of comma separated numbers, a range of numbers or a single number.
Where your input stream is character based -c can be a better option than selecting by bytes as often characters are more than one byte.
In the following example character ‘♣’ is three bytes. By using the -c option the character can be correctly selected along with any other characters that are of interest.
echo '♣foobar' | cut -c 1,6
♣a
echo '♣foobar' | cut -c 1-3
♣fo
How to cut based on a delimiter
To cut using a delimiter use the -d option. This is normally used in conjunction with the -f option to specify the field that should be cut.
In the following example a CSV file exists and is saved as names.csv.
John,Smith,34,London
Arthur,Evans,21,Newport
George,Jones,32,Truro
The delimiter can be set to a comma with -d ','. cut can then pull out the fields of interest with the -f flag. In the following example the first field is cut.
cut -d ',' -f 1 names.csv
John
Arthur
George
Multiple fields can be cut by passing a comma separated list.
cut -d ',' -f 1,4 names.csv
John,London
Arthur,Newport
George,Truro
How to cut by complement pattern
To cut by complement us the --complement option. Note this option is not available on the BSD version of cut. The --complement option selects the inverse of the options passed to sort.
In the following example the -c option is used to select the first character. Because the --complement option is also passed to cut the second and third characters are cut.
echo 'foo' | cut --complement -c 1
oo
How to modify the output delimiter
To modify the output delimiter use the --output-delimiter option. Note that this option is not available on the BSD version of cut. In the following example a semi-colon is converted to a space and the first, third and fourth fields are selected.
echo 'how;now;brown;cow' | cut -d ':' -f 1,3,4 --output-delimiter=' '
how brown cow
Further reading
- cut man page
- 10 Practical Linux Cut Command Examples to Select File Columns
- Linux and Unix cut command
- Cut Command in Unix ( Linux) Examples
