Gentoo Development Guide

cut -- Column Concatenation

The cut tool can be used to extract specific columns from files which are delimited by a particular character or by column numbers. It can be passed filenames on the commandline; if none are specified, it reads from stdin.

The cut tool considers the first character in a line to have index 1. The -c, -f and -b switches take a parameter listing the desired columns. This can be a single value, or a more complex list of values separated by commas. Each value can be a single number, or two numbers separated by hyphens representing low-high. If low is unspecified, it is treated as the first column. If high is unspecified, it is treated as being "up to the last character (inclusive)".

To select particular characters from each line, use the -c switch. For particular bytes (not the same as characters when using multibyte text), use -b. To specify particular fields, use -f.

When using -f, the field delimiter can be specified using the -d switch. The default value is the tab character. The -s switch instructs cut to suppress lines which do not contain any instances of the delimiter — by default they are echoed intact.

For example, to extract the second, fourth and fifth columns in a comma-delimited file, ignoring lines which contain no commas, one could use:

cut -s -d',' -f2,4-5 input.txt > output.txt

To chop the first character off stdin, one could use:

do_stuff | cut -c2-

See the cut manpage and IEEE1003.1-2004-cut for full documentation.