Nl (Unix)

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.