A Quick Introduction to Unix/Special Directories

The abbreviated directories . and ..

The directories named . and .. are relative names. They are interpreted by the shell in the current context. While this takes a moment or two longer to grasp than ordinary absolute directory names, it is a very useful thing about Unix. In any directory you can type

% ls -a

As you will see, there are two directories listed called (.) and (..). These appear in all Unix directories.

Current directory (.)

In Unix . means the current directory, so typing

% cd .

means that you stay where you are.

This may not seem very useful at first, but you will often find it very useful – remember that it is a relative directory name.

Parent directory (..)

.. means the parent of the current directory, so typing

% cd ..

will take you up one directory.

Home directory (~)

Typing cd alone or cd ~ always returns you to your home directory. This is very useful if you are lost in the file system. Typing cd / takes you to the root.

What do you think

% ls ~/..

would list?