join(t, @F)

##</code><code>##

    F='  '  # Enter a tab here.
    perl -F"$F" -i -wlne "munge(@F); print join('$F',@F);" file

##</code><code>##

   perl -F"$F" -i -wlpe 'munge(@F); $_ = join("'$F'",@F);'