Customising the User prompt

The user prompt is that thing which you see once you've logged in and the system is waiting for you to do something useful. It may look like this..

..woo-hoo! Or even this..

Exciting eh? No. It's not exciting. It's crap. But you can change all this and get your street-cred back just by adding a single file.

The prompt can be configured to tell you useful stuff, like who you are (saves having to type whoami all the time, if you swap between users regularly) or which directory you're currently logged into (saves having to type pwd all the- you get the idea).

There are a few ways to do it. The prompt is influenced by which shell you're currently using and I would urge you to install and use bash 'cos the default csh is really shit. Come back when you've finished..

OK so you've wisely installed bash like I suggested. Log in and type cd to take you to your home directory (/home/username or /root if you're logged in as root). The bash shell will parse a file called .bash_profile if it exists in your home directory and you can create this file to influence the shell's behaviour. Thus..

vi .bash_profile

Note the leading dot 'cos it's a hidden file. This is what I've got in my own .bash_profile..

..and this is all you'll need too. Yep, just one line. Not so hard eh..

What does it all mean? Well the PS1= is the bit which tells the shell to configure the prompt somehow. The rest is what you'd like to see.

In the case of my example above, \u means "the logged in user", @ means @ and \w means "the currently logged directory". Finally we have the usual "$" sign, which reminds us of all the money (and stress)(and downtime) we're saving from using Unix instead of Windows. And of course, the whole thing's enclosed in double quotes " " just like any self-respecting regular expression should be. Just make sure the prompt's not too long or your commands may wrap to the next line and that would be no fun.

BASH Prompt Parameters

When executing interactively, bash  displays  the  primary prompt  PS1  
when  it  is ready to read a command, and the secondary prompt PS2 when 
it needs more input to  complete a  command.   Bash  allows these prompt 
strings to be customized by inserting a number of backslash-escaped special
characters that are decoded as follows:

\a  an ASCII bell character (07)
\d  the  date  in  "Weekday  Month  Date" format (e.g., "Tue May 26")
\e  an ASCII escape character (033)
\h  the hostname up to the first `.'
\H  the hostname
\n  newline
\r  carriage return
\s  name of the shell, the  basename  of  $0 (the portion following the final slash)
\t  the current time in 24-hour HH:MM:SS format
\T  the current time in 12-hour HH:MM:SS format
\@  the current time in 12-hour am/pm format
\u  the username of the current user
\v  the version of bash (e.g., 2.00)
\V  the  release  of  bash, version + patchlevel (e.g., 2.00.0)
\w  the current working directory
\W  the basename of the current  working  directory
\!  the history number of this command
\#  the command number of this command
\$  if  the effective UID is 0, a #, otherwise a $
\nnn the character  corresponding  to  the  octal number nnn
\\  a backslash
\[  begin a sequence of non-printing characters, which could be used to embed a 
    terminal control sequence into the prompt
\]  end a sequence of non-printing characters

BASH Command Files