Joseph Herlant
version 1.0.0, 2013-10-19 : Initial version

This shell command prints out the lines of the input, preceeding it with the line numbers, like the nl command do.

perl -pe 's//$. /' input

If you want exactly the same output than nl (meaning the same spacing at the begining of the line with a right-aligned line number), you can also use this command:

perl -pe 'printf "% 6d  ",$.' input