File: sed.info,  Node: cat -b,  Next: wc -c,  Prev: cat -n,  Up: Examples

7.12 Numbering Non-blank Lines
==============================

Emulating ‘cat -b’ is almost the same as ‘cat -n’--we only have to
select which lines are to be numbered and which are not.

   The part that is common to this script and the previous one is not
commented to show how important it is to comment ‘sed’ scripts
properly...

     #!/usr/bin/sed -nf

     /^$/ {
       p
       b
     }

     # Same as cat -n from now
     x
     /^$/ s/^.*$/1/
     G
     h
     s/^/      /
     s/^ *\(......\)\n/\1  /p
     x
     s/\n.*$//
     /^9*$/ s/^/0/
     s/.9*$/x&/
     h
     s/^.*x//
     y/0123456789/1234567890/
     x
     s/x.*$//
     G
     s/\n//
     h