nl (Unix)
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nl is a Unix utility for numbering lines, either from a file or from standard input, reproducing output on standard output.
It has a number of switches:
- a - number all lines
- t - number lines with printable text only
- n - no line numbering
- string - number only those lines containing the regular expression defined in the string supplied.
The default applied switch is t.
nl also supports a number of command line options.
[edit] Example
$ nl tf
1 echo press cr
2 read cr
3 done
The following example numbers only the lines that begin with a capital letter A (matching on the regular expression /^A/). filename is optional.
$ nl -b p^A filename
apple
1 Apple
BANANA
2 Allspice
strawberry
[edit] See also
- wc - the word count command
- cat - concatenate command (-n flag is equivalent to nl -a)
- List of Unix programs
