Question

I accidently types cd // and was surprised to see OS X take me to a directory called //. It appears to be the root directory, but I am wondering why the cd // command did not throw an error.

Does // have any special meaning?

Seans-MacBook-Pro:/ sean$ cd //
Seans-MacBook-Pro:// sean$ pwd
//
Seans-MacBook-Pro:// sean$ ls
Applications            archive             net
Incompatible Software       bin             opt
Library             cores               private
Network             dev             sbin
System              etc             tmp
User Guides And Information home                usr
Users               mach_kernel         var
Volumes             mds
Seans-MacBook-Pro:// sean$ cd /
Seans-MacBook-Pro:/ sean$ ls
Applications            archive             net
Incompatible Software       bin             opt
Library             cores               private
Network             dev             sbin
System              etc             tmp
User Guides And Information home                usr
Users               mach_kernel         var
Volumes             mds

EDIT

I also noticed that cd ///, cd //// etc all resolve to root, and do not give an error. Only cd // is registered as being in the // directory.

Seans-MacBook-Pro:~ sean$ cd ///
Seans-MacBook-Pro:/ sean$ cd //
Seans-MacBook-Pro:// sean$ 

Answer 1

The / character is used as a separator, and – generally – any number of them can be collapsed into a single one. (This happens at the shell level, so when bash is parsing your input, for example)

This is also another way to write /Users/Sean/ – ////Users////Sean//. However, the “//” is slightly special in some cases. You’re still at the root (/) but bash does not collapse it immediately.

For more information, see this SuperUser post:
https://superuser.com/questions/389338/which-directory-does-path-represent-in-linux