Lets you see what’s in /.
cd
Typing cd with no arguments selects your home directory— /home/ yourname —as the current working directory. Try pwd to verify this.
Before continuing, you should know that there are actually two different kinds of filenames. Some of them begin with /, the root directory, such as /etc/profile. These are called absolute filenames because they refer to the same file no matter what your current directory is. The other kind of filename is relative.
Two directory names are used only in relative filenames: . and ... The directory . refers to the current directory, and .. is the parent directory. These are “shortcut” directories. They exist in every directory. Even the root directory has a parent directory—it’s its own parent!
So filenames that include . or .. are relative, because their meaning depends on the current directory. If I’m in /usr/bin and type ../etc, I’m referring to /usr/etc. If I’m in /var and type ../etc, I’m referring to /etc. Note that a filename without the root directory at the front implicitly has ./ at the front. So you can type local/bin, or ./local/bin and it means the same thing.
A final handy tip: The tilde ~ is equivalent to your home directory. So typing cd ~ is the same as typing cd with no arguments. Also, you can type things like cd ~/practice/mysubdirectory to change to the directory /home/yourname/practice/mysubdirectory. In a similar way, ~myuser is equivalent to the home directory of the user “myuser,” which is probably something like /home/myuser; so ~myuser/docs/debian.ps is equivalent to /home/myuser/doc/debian.ps.
Here are some more file commands to try out, now that you know about relative filenames. cd to your home directory before you begin.
mkdir practice
In your home directory, make a directory called practice. You’ll use this directory to try out some other commands. You might type ls to verify that your new directory exists.