25.12 Double Space, Triple Space ...

Here are handy scripts for printing drafts of files. They double-space or triple-space file(s) or standard input. For example:

% doublespace afile | lp
% prog | triplespace | lp

doublespace   triplespace

#!/bin/sed -f   #!/bin/sed -f
G   G
   G

No, that isn't a typo: both scripts just use the sed command G (34.24). The G command appends a newline and the contents of sed's hold space, which will be empty in this script. The effect is to add a newline after every newline; two Gs add two newlines.

That file doesn't even use a shell, so it's efficient; the kernel starts sed directly (45.3) and gives it the script itself as the input file expected with the -f option. If your UNIX can't execute files directly with #!, type in these versions instead:

doublespace   triplespace
exec /bin/sed G ${1+"$@"}   exec /bin/sed 'G;G' ${1+"$@"}

They start a shell, then exec replaces the shell with sed (45.7). The ${1+"$@"} works around a problem with argument handling (46.7) in some Bourne shells.

And now you know how to make quadruplespace, quintuplespace, ... :-).