Double Dash

If you’re anything like me you’ll find your directories liberally scattered with some pretty strange directory and file names.

$ ls -la

-rw-r--r--   1 gypsydave5  1482096370   647 11 Oct 20:15 :w
drwxr-xr-x   2 gypsydave5  1482096370    68 10 Feb 08:55 -p/
-rw-r--r--   1 gypsydave5  1482096370  2900 11 Oct 20:15 \(

Hopefully you’re nothing like me and you never get this, but I’m both a sloppy and impatient typist and so I will occasionally often mash the keyboard in Vim and name a file after the write command, or somehow create a directory called -p because I was using the recursive flag on mkdir.¹

On that subject, let’s try and get rid of the -p directory:

$ rm -rf -p

rm: illegal option -- p
usage: rm [-f | -i] [-dPRrvW] file ...
       unlink file

Hmmm, that sucks. What about…

$ rm -rf "-p"

rm: illegal option -- p
usage: rm [-f | -i] [-dPRrvW] file ...
       unlink file

Boo. Happily there’s a *nix convention to help with these situations: --. Double-dash tells the command you’re running that everything that comes after it is not to be treated as a command option, but is instead a filename. So:

$ rm -rf -- -p
$ ls -la

-rw-r--r--   1 gypsydave5  1482096370   647 11 Oct 20:15 :w
-rw-r--r--   1 gypsydave5  1482096370  2900 11 Oct 20:15 (

DISCO!

This behaviour is implemented in most of the command line tools you’ll use on a *nix system - it’s useful to know.