=============================
Setting the BASH shell prompt
=============================
-Ian! D. Allen - idallen@idallen.ca - www.idallen.com

If you have several Unix machines in your lives and you use remote login,
you may be uncertain about which machine is receiving your keystrokes.

For Bourne-style shells (including BASH) you can change the shell prompt
string to anything you like by changing the contents of environment
variable PS1, e.g.:

    $ PS1='Yes Master? '
    Yes Master? date
    Fri Jan 19 10:36:30 EST 2007
    Yes Master? 

The BASH shell uses special escape sequences in the prompt string to
mean things such as your userid ("\u"), your host name ("\h"), and the
last part of the pathname that is your current working directory ("\W").
(See the BASH man page for lots of other goodies.)

In the following sequence of commands issued on machine "foobar", you
can see the original PS1 contents and the new contents and how each
affects the prompt being displayed (note the use of single quotes):

    bash-2.04$ hostname
    foobar
    bash-2.04$ 
    bash-2.04$ echo "$PS1"
    \s-\v\$
    bash-2.04$ PS1='[\u@\h \W]\$ '
    [idallen@foobar idallen]$ cd /tmp
    [idallen@foobar tmp]$ 

As with the value of any shell variable, this change to PS1 vanishes
when this shell exits.  To make a variable change permanent across
logout/login, you must add the line that sets PS1 to one of your login
script files (e.g. to the file .bash_profile in your home directory) and
also export the PS1 variable to allow other child shells to inherit it:

  In file .bash_profile in your home directory add these lines:

    PS1='[\u@\h \W]\$ '
    export PS1

The above lines will be executed every time you log in, and the PS1
variable will be exported to all subshells of the login shell.

You can also set the prompt in the $HOME/.bashrc file, which will affect
every BASH shell you run, not just shells that are children of your
login shell.

The Linux file /etc/profile often contains script that sets your
prompt for you.  Look at it for ideas.