bash Cookbook

Decoding the Prompt

Problem

You’d like to know what all the punctuation on your screen means.

Solution

All command-line shells have some kind of prompt to alert you that the shell is ready to accept your input. What the prompt looks like depends on many factors including your operating system type and version, shell type and version, distribution, and how someone else may have configured it. In the Bourne family of shells, a trailing $ in the prompt generally means you are logged in as a regular user, while a trailing # means you are root. The root account is the administrator of the system, equivalent to the System account on Windows (which is even more powerful than the Administrator account), or the Supervisor account on Netware. root is all-powerful and can do anything on a typical Unix or Linux system.

Default prompts also often display the path to the directory that you are currently in; however, they usually abbreviate it. So a ~ means you are in your home directory. Some default prompts may also display your username and the name of the machine you are logged into. If that seems silly now, it won’t when you’re logged into five machines at once possibly under different usernames.

Here is a typical Linux prompt for a user named jp on a machine called adams, sitting in the home directory. The trailing $ indicates this is a regular user, not root.

jp@adams:~$

Here’s the prompt after changing to the /tmp directory. Notice how ~, which really meant /home/jp, has changed to /tmp.

jp@adams:/tmp$ ...