expand
and
unexpand
$tabstop
= 4; @lines_without_tabs
=
expand;
@lines_with_tabs
= unexpand;
expand
and
unexpand
do. Given a line with tabs in it, expand will replace
the tabs with the appropriate number of spaces. Given a line with or
without tabs in it, unexpand will add tabs when it can save bytes by doing
so. Invisible compression with plain ascii!