HOWTO: Customizing bash prompt

[MiCovran]

If you have difficulties using the terminal because the prompt isn't visible enough or you would simply like it to look nicer, this howto is for you. It should work on any distribution if you use bash shell, just don't expect your existing .bashrc file to look like Ubuntu's. I've attached a before and after picture of my terminal as an example of what you could do.

So let's get started. Fire up your terminal and stay in your home directory.


1. Backup

First, let's backup our .bashrc file since we're about to make some changes to it:

cp .bashrc .bashrc-backup

The .bashrc file tells bash what to do when terminal is started, including how to show prompt.


2. Preparing the .bashrc

Use your favorite text editor to edit the original .bashrc file, eg.:

gedit .bashrc

Find this part:

if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fi

Bash reads PS1 variable to see how to show primary prompt and PS2 for a secondary prompt (used when writing multi-line commands). In this "if" block, the first PS1 is a prompt which will be shown when color is turned on, and the second one (after "else") is being used when no color is desired. As you can see, color codes are quite tiring to use. Imagine you have to write things like \[\033[01;32m\] all over again. It's horrible. Fortunetly, bash lets us define variables that make our life easier. So paste this code above that "if" block:

# ANSI color codes
RS="\[\033[0m\]"    # reset
HC="\[\033[1m\]"    # hicolor
UL="\[\033[4m\]"    # underline
INV="\[\033[7m\]"   # inverse background and foreground
FBLK="\[\033[30m\]" # foreground black
FRED="\[\033[31m\]" # foreground red
FGRN="\[\033[32m\]" # foreground green
FYEL="\[\033[33m\]" # foreground yellow
FBLE="\[\033[34m\]" # foreground blue
FMAG="\[\033[35m\]" # foreground magenta
FCYN="\[\033[36m\]" # foreground cyan
FWHT="\[\033[37m\]" # foreground white
BBLK="\[\033[40m\]" # background black
BRED="\[\033[41m\]" # background red
BGRN="\[\033[42m\]" # background green
BYEL="\[\033[43m\]" # background yellow
BBLE="\[\033[44m\]" # background blue
BMAG="\[\033[45m\]" # background magenta
BCYN="\[\033[46m\]" # background cyan
BWHT="\[\033[47m\]" # background white

Now you don't have to write all that ANSI code over and over again. For instance, you can just use $FBLE to set foreground (text) to blue, instead of \[\033[34m\].


3. Setting the prompt without color

Now that you have this prepared, you can design your own prompt. Let's start with the one without color for simplicity (it's the one just below the "else" line). First, comment in the default PS1 that's already there to ignore it (put a # in front of the line), and then define your own PS1 and PS2 just below it.

I'll explain how I did mine. This is how they are defined:

PS1="[ ${debian_chroot:+($debian_chroot)}\u: \w ]\\$ "
PS2="> "

Secondary prompt is simple. It shows just >.
However, the primary one is a little bit more complicated. It contains some special characters for additional info about a session. You can find a list of those special characters in bash's man page under section PROMPTING:

man bash

I used \u (username), \w (current working directory) and, of course, \\$ (the $ or # symbol, depending on your privileges). You don't need to worry about what "${debian_chroot:+($debian_chroot)}" means, just always copy-paste it in front of "/u". So my primary prompt will be shown like this (when I'm in my home directory): [ penguin: ~ ]$


4. Setting the prompt with color

If you want to use a colored prompt, you must find the line in your .bashrc that says #force_color_prompt=yes and remove # from it. This means that bash will from now on prefer what is defined above the "else" line. Comment in the old PS1 that's located there just like you did before, and then copy-paste your PS1 and PS2 from below "else" (colorless versions). You now have the base layout and you just need to add some color to it.

The simplest way to deal with it is by inserting variables from that big chunk of code you pasted before. First put a $RS at the end of both PS1 and PS2 so you don't change formating of other text in the terminal. All ANSI color codes change only the text behind them, and you can only turn off $HC, $UL and $INV codes by using $RS. Here's how I added color to my prompt:

PS1="$HC$FYEL[ $FBLE${debian_chroot:+($debian_chroot)}\u$FYEL: $FBLE\w $FYEL]\\$ $RS"
PS2="$HC$FYEL> $RS"

I used hicolor at the beginning and left it on until that last $RS. Then I just switched between colors I wanted (blue and yellow). So I got this prompt: [ penguin: ~ ]$

When you want to see what you've done, just save changes to .bashrc file, start another terminal and enjoy your new prompt. If you want to see how your secondary prompt looks like, enter just \ as a command in the terminal.

Tip: If you're using gnome-terminal and want to fine tune your color selection, right click the terminal, choose Edit Current Profile... and go to Colors tab. Note that these changes effect the complete terminal, not just prompt. I don't know how to do this for any other terminal emulators, I'm a GNOME man.


5. Reverting to old settings

If for some reason you wish to return the old prompt or if you broke your .bashrc, the easiest way is to just recover old .bashrc file you backed up. Run a terminal and use:

cp .bashrc-backup .bashrc

Voila! Everything is back to normal.


For the end

I tried to make this howto as simple to understand as I could. If you don't understand or don't know how to do something, if you have a suggestion or think I made a mistake somewhere, feel free to contact me. This is the first howto I wrote so any feedback is appreciated.
This is just my small way to say thanks to people in this forum who helped me a lot, so ... thanks.

[tzulberti]

Great How-to.... I will try to customize it...

Thanks.

[mfolnovic]

this is great, when I get home, I'll try it

[MiCovran]

Originally Posted by tzulberti I will try to customize it...

Originally Posted by mfolnovic when I get home, I'll try it

Let me know how it worked.

BTW, I felt like section 3 - setting the prompt - wasn't clear enough for people with no scripting or programming experience, so I rewrote it in a more "step-by-step" approach.

[Trezker]

Good stuff, now I can finally see where my latest compile results start.

[MiCovran]

Originally Posted by Trezker Good stuff, now I can finally see where my latest compile results start.

That's the primary reason why I got into it too.

[uvdevnull]

Thanks for that MiCovran, very helpful!

Just a small correction... The ANSI color variables must be defined prior to the prompts that use them, otherwise it doesn't work, at least for me. So they can't be pasted at the end of file, but anywhere before the first attempted usage.

Thanks again,
uvdevnull

[h711]

wat a great tutorial..do u have any customization??..plz share..

[binbash]

Great howto, thanks!

[MiCovran]

Originally Posted by uvdevnull The ANSI color variables must be defined prior to the prompts that use them

I did write what you told in the howto. I've put it in bold now so it will be easier to spot.

Originally Posted by h711 wat a great tutorial..do u have any customization??..plz share..

It's actually quite simple to customize it, you just have to play a little bit.

For changing the colour of the prompt just play with all the different variables you pasted into your .bashrc file (it's that big chunk of code from the howto). For instance, if you want to change colour of text in some part of the prompt to green, first find the "foreground green" line. There you'll see that the variable name is "FGRN" (on the beginning of the line). Then just add "$FGRN" before the text you want to change (in the "PS1" variable).

However, if you want to change contents of the prompt, then take a look at the bash man file (also available at this page):

man bash

Find the "PROMPTING" section and there you'll see all the features that your prompt can have. When you find what you like, just put it in the "PS1" variable in your .bashrc file. So if you would like your prompt to show time, you could just add "\t" to the beginning of the "PS1" variable. And if you want to add some text or some brackets (or basically anything), you can just type it as it is.

As an example, PS1="$FGRN(My first bash prompt) \t $RS" would simply show "(My first bash prompt)" and current time after it. All in green, of course.