BASH Shell Change The Color of Shell Prompt on Linux or UNIX

Task: Displaying current BASH prompt (PS1)

Use the echo command/printf command to display current BASH prompt settings:
$ echo "$PS1"
## OR ##
$ printf "%s\n" "$PS1"
Here is what I see:

[\\u@\h \\W]\\$

Here is another output from my Debian based system:
$ echo $PS1
Ubuntu/Debian based Linux distro displayed the following:

\[\e]0;\u@\h: \w\a\]${debian_chroot:+($debian_chroot)}\u@\h:\w\$

By default the command prompt is set to [\u@\h \W]\$. The backslash-escaped special characters are decoded as follows:

• \u: Display the current username .
• \h: Display the hostname
• \W: Print the base of current working directory.
• \$: Display # (indicates root user) if the effective UID is 0, otherwise display a $.

Task: Modifing current BASH prompt

Before you modify settings save your old prompt using the following command:
oldps1="$PS1"
So if you messed up, you can switch back easily using the following syntax:
PS1="$oldps1"
Use the export command to setup a new shell prompt:
$ export PS1="[\\u@\\H \\W \\@]\\$ "

Fig.01: New prompt in action

Where,

• \H: Display FQDN (fully qualified domain name) hostname.
• \@: Display current time in 12-hour am/pm format.

Task: Adding colors to the prompt

To add colors to the shell prompt use the following export command syntax:
'\e[x;ym $PS1 \e[m'
Where,

• \e[ : Start color scheme.
• x;y : Color pair to use (x;y)
• $PS1 : Your shell prompt variable.
• \e[m : Stop color scheme.

Change the color of shell prompt by setting the PS1

To set a red color prompt, type the following export command:
$ export PS1="\e[0;31m[\u@\h \W]\$ \e[m "

Fig.02: Adding the colors to the prompt

A list of color codes

Note: You need to replace digit 0 with 1 to get light color version.

Task: How do I make the prompt setting permanent?

Your new shell prompt setting set by $PS1 is temporary i.e. when you logout setting will be lost. To have it set every time you login to your workstation add above export command to your $HOME/.bash_profile file or $HOME/.bashrc file.
$ cd
$ vi .bash_profile

OR
$ vi $HOME/.bashrc
Append the following line:
export PS1="\e[0;31m[\u@\h \W]\$ \e[m"
Save and close the file in vim/vi.

Bash Change The Color of Shell Prompt Example

Add the following command in ~/.bashrc:

# let us setup prompt
export PS1="\[\e[32m\][\[\e[m\]\[\e[31m\]\u\[\e[m\]\[\e[33m\]@\[\e[m\]\[\e[32m\]\h\[\e[m\]:\[\e[36m\]\w\[\e[m\]\[\e[32m\]]\[\e[m\]\[\e[32;47m\]\\$\[\e[m\] "

You will get prompt as follows:

Here is another example that include exit status of command as well:

# 
#\u - user name
#\h - short hostname
#\W - current working dir
#\? - exit status of the command
export PS1="{\[\e[32m\]\u\[\e[m\]@\[\e[36m\]\h\[\e[m\]:\W_\$?}$ "

Say hello to tput command

You can also use tput command to set terminal and modify the prompt settings. For example, to display RED color prompt using a tput:
export PS1="\[$(tput setaf 1)\]\u@\h:\w $ \[$(tput sgr0)\]"
However, we do not hard-code ANSI color escape sequences. Hence we use the tput command as follows:

_GREEN=$(tput setaf 2)
_BLUE=$(tput setaf 4)
_RED=$(tput setaf 1)
_RESET=$(tput sgr0)
_BOLD=$(tput bold)
export PS1="${_GREEN}\h${_BLUE}@${_RED}\u${_RESET} ${_BOLD}\$ ${_RESET}"

Here is a list of handy tput command line options

• tput bold – Bold effect
• tput rev – Display inverse colors
• tput sgr0 – Reset everything
• tput setaf {CODE}– Set foreground color, see color {CODE} table below for more information.
• tput setab {CODE}– Set background color, see color {CODE} table below for more information.

Various color codes for the tput command

Customize bash colors prompt content in Linux or Unix terminal

My current PS1 settings from the ~/.bash_aliases file on Ubuntu Linux desktop displayed using the cat command:
$ cat ~/.bash_aliases
Config that changes the color of shell prompt as per my needs along with the Tux ASCII logo.

export PS1="\[\e[31m\][\[\e[m\]\[\e[38;5;172m\]\u\[\e[m\]@\[\e[38;5;153m\]\h\[\e[m\] \[\e[38;5;214m\]\W\[\e[m\]\[\e[31m\]]\[\e[m\]\\$ "
 
cat<<'EOF'
           _..._
         .'     '.
        /  _   _  \
        | (o)_(o) |
         \(     ) /
         //'._.'\ \
        //   .   \ \
       ||   .     \ \
       |\   :     / |
       \ `) '   (`  /_
     _)``".____,.'"` (_
     )     )'--'(     (
      '---`      `---`
EOF

Which will produce:

My customized and colorized bash prompt

Conclusion

You learned how change the color of shell prompt under Linux and Unix when using bash. For more information see the following resources:

• HowTo: Change or setup your bash custom prompt (PS1) – This tutorial explains how-to customizing a bash shell to get a good looking prompt, configure the appearance of the terminal and apply themes using bashish package.
• man page – bash