fancy bash prompt with colors, trimmed CWD and git status

.bashrc

# Shows exit status in red if previous command exited with
# an error code, the CWD in blue up to 30 chars or the 3 parent
# directories, and the git branch and status in grey, if in a
# git repo.

PS1="\n[\u@\h \[\e[1;31m\]\$(_exit_status)\[\e[0m\]\[\e[0;36m\]\$(_short_dir \w)\[\e[0m\]\[\e[1;30m\]\$(_git_status)\[\e[0m\]]\\$ "

# Return the exit status with padding if exit status != success
_exit_status() {
    exit_status=$?
    if [[ $exit_status != "0" ]]
    then
        echo "$exit_status "
    fi
}

# Return only 3 parent dirs if CWD > 30 chars
_short_dir() {
    cwd=${PWD/#$HOME/\~}
    if [ ${#cwd} -gt 30 ]
    then
        cwd="...$(expr match $cwd '.*\(/.*/.*/.*\|.\{30\}\)$')"
    else
        echo "$cwd"
    fi
}

# GIT prompt
export GIT_PS1_SHOWDIRTYSTATE=true
export GIT_PS1_SHOWUNTRACKEDFILES=true
export GIT_PS1_SHOWSTASHSTATE=true
_git_status() {
    declare -F __git_ps1 &>/dev/null && __git_ps1 ' (%s)'
}