Here’s something fun I discovered by accident. When you typo a path with double forward slashes in a bash prompt with a default PS1 listing the working directory with
\w, you get double slashes:
user@machine /path/$ cd // user@machine //$
This also happens in sh on Linux and Mac OS X, presumably because sh aliased to bash.
$ cd // $ pwd ==> //
This is not the case in tcsh:
[machine:/path/] user% cd // [machine:/] user%
Or with Almquist sh on FreeBSD:
$ cd // $ pwd ==> /
But it gets funky if we chain shells. If we start with bash, then launch tcsh, the current double slash working directory is preserved:
user@machine /path/$ cd // user@machine //$ tcsh [machine://] user%
I haven’t tried with zsh or fish.