A / at the end of the name of a directory/folder is optional. Most of the time, including or omitting the final slash in a directory name does not change the effect of a command.

So cd ../ is equivalent to cd ...

Paths that don't start with a / are relative paths; they are resolved relative to the current directory.

Every directory has two special entries:

• a directory entry called . that resolves to the directory itself


• a directory entry called .. that resolves to the directory's parent (i.e., the directory that contains that directory)

Therefore cd ../ and cd .. change directory to the parent of the current directory. Thus, if you start out in /home/fazlan and run cd .. or cd ../, you'll end up in /home.

In contrast, /.. is an absolute path (albeit an unusual one). / is the filesystem root--the directory you get to if you go up in the directory hierarchy all the way. (Using the same parent and child metaphor, we say / is the ancestor of everything in the filesystem.)

Since .. means "the parent directory of this directory" and / means "the top of the filesystem," /.. means "the parent directory of the top of the filesystem."

But what does it mean to talk about the directory that contains /? Well, / is an exception. Since no directory contains it, we say that /'s parent is itself. Therefore, in /, .. is /. Consequently, /.. is the same as /.

This is why cd ../ brings you up one directory from where you started, while cd /.. brings you to the very top. More elegant and easily read ways to do these things are cd .. and cd /, respectively.