Toggle format of gnome terminal prompt string by command?

My terminal has a default prompt format like this one:

username@boxname /path/to/current/directory $

The code that produces it looks like this: (it has some color definitions too)

PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[01;34m\] \w \$\[\033[00m\]'

If the path to the current directory gets too long it becomes unpleasant to work with the terminal because you constantly break lines. In such cases I would prefer a format that produces a shorter string like this one:

username@boxname current_dir_name $

The code that produces it would look like this (again with color):

PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[01;34m\] $(basename ${PWD}) \$ \[\033[00m\]'

Does anyone know how I could easily toggle the format of the current terminal window from one style to the other by just typing for example: prompttoggle?

Store both your long and short PS1 variables under a different name:

PS1short='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[01;34m\] \w \$\[\033[00m\]'
PS1long='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[01;34m\] $(basename ${PWD}) \$ \[\033[00m\]'

Make sure to set PS1to one of them initially:

PS1="$PS1long"

Then you can make an alias like this to toggle between the two PS1 values:

alias prompttoggle='if test "$PS1" = "$PS1long" ; then PS1="$PS1short" ; else PS1="$PS1long" ; fi'

Adding all four lines to your ~/.bashrc file will ake the command available in your Bash sessions, here are they again for easier copying:

PS1short='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[01;34m\] \w \$\[\033[00m\]'
PS1long='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[01;34m\] $(basename ${PWD}) \$ \[\033[00m\]'
PS1="$PS1long"
alias prompttoggle='if test "$PS1" = "$PS1long" ; then PS1="$PS1short" ; else PS1="$PS1long" ; fi'

You can use a tiny bash function:

prompttoggle () { 
    if [[ $PS1 = *basename* ]]; then 
        export PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[01;34m\] \w \$\[\033[00m\]'
    else 
        export PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[01;34m\] $(basename ${PWD}) \$ \[\033[00m\]'
    fi ;}

The function above matches if the current $PS1 contains basename, if yes, then the PS1 without basename is set otherwise the one with basename is set.

Put the function in your ~/.bashrc to get it available in all interactive sessions.

Example:

foo@bar:~/spam/egg$ prompttoggle () { 
>     if [[ $PS1 = *basename* ]]; then 
>         export PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[01;34m\] \w \$\[\033[00m\]'
>     else 
>         export PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[01;34m\] $(basename ${PWD}) \$ \[\033[00m\]'
>     fi ;}

foo@bar:~/spam/egg$ prompttoggle 

foo@bar egg $ prompttoggle

foo@bar ~/spam/egg $

Or... make two very tiny functions and add to the end of your ~/.bashrc

# short prompt
promptshort() { export PS1=$(echo "$PS1" | sed 's/\\w/\\W/g') ; }

# full length prompt
promptlong() { export PS1=$(echo "$PS1" | sed 's/\\W/\\w/g') ; }

for a shortened prompt, type promptshort, to go back to the full path, type promptlong

\W shows the current working directory only so $(basename ${PWD}) is overkill imho

You could combine into one function but "long" and "short" are descriptive and both have less keystrokes than "toggle" ;)

Instead of adding a line to override PS1 I prefer to tweak the code that sets it (for example, uncomment force_color_prompt=yes and edit the line after [ "$color_prompt" = yes ]; then)

Here's a ~/.bashrc function definition that I personally use to reset/toggle my prompt from regular prompt to just $. Adapt it as necessary to suit your needs.

resetps() {
    if [ "$PS1" = "$ " ] 
    then
        PS1=$OLDPS1 
    else
        OLDPS1=$PS1 
        export OLDPS1 
        PS1="$ " 
    fi 
}