Nl (Unix)

Updated on Nov 13, 2023

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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 some command line options.

Example

The following example numbers only the lines that begin with a capital letter A (matching on the regular expression /^A/). filename is optional.

It can be useful as an alternative to grep -n:

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