UNIX for Dummies Questions & Answers

Many times over the years, I've noticed that if I accidentally type 'cd //', my bash prompt will display that I am in // instead of /. If I do an ls command, it looks just like I'm in /. So this morning I decided to try and do 'cd ///' all the way up to a full 'cd //////'. None of those attempts did the same thing as //. Knowing that nearly everything in *nix seems to have a real purpose, I suspect // really means something slightly different from /. Are there any long time *nix users who might know the history? I've only been using *nix for ten years and haven't a clue.

/ is a separator between components of a pathname. Consider /usr/bin/ksh. The leading slash tells you that this is a absolute pathname so you start at root and look for "usr". Then you look in "usr" for "bin". The path known as / is a little special. The leading slash says it's an absolute path so we start at root. And then we're done. With a path like /usr/bin//ksh you have superfluous separators. A path like that is not guaranteed to work so you shouldn't do it. But superfluous separators are easy to ignore and this is commonly done. The path // is a special case of a path with superfluous separators.

Code:

$ cd //
$ cd ///
$ cd //////
$ cd /////////
$ /usr/bin/pwd
/
$