LINUX HACK 29

Chapter 5: PS1, PS2, PS3, PS4 and

PROMPT_COMMAND

Hack 29. PS1 - Default Interaction Prompt

The default interactive prompt on your Linux can be modified as shown below to something useful and informative. In the following example, the default PS1 was “\s-\v\$”, which displays the shell name and the version number. Let us change this default behavior to display the username, hostname and current working directory name as shown below.

-bash-3.2$    export  PS1="\u@\h  \w>  "

ramesh@dev-db  ~>  cd  /etc/mail

ramesh@dev-db  /etc/mail>

[Note: Prompt changed to "username@hostname current-dir>" format]

Following PS1 codes are used in this example:

o    \u – Username

o    \h – Hostname

o    \w - Full pathname of current directory. Please note that when you are in the home directory, this will display only ~ as shown above

Note that there is a space at the end in the value of PS1. Personally, I prefer a space at the end of the prompt for better readability.

Make this setting permanent by adding export PS1=”\u@\h \w> ” to either

.bash_profile (or) .bashrc as shown below.

ramesh@dev-db  ~>  vi  ~/.bash_profile

ramesh@dev-db  ~>  vi  ~/.bashrc

[Note: Add export PS1="\u@\h \w> " to one of the above files]

Refer to the next chapter for several practical examples of PS1 usage in detail.