bashrc prompt pwd shortener

bashrc_prompt_shortener

# prompt shortener : http://stackoverflow.com/questions/3497885/code-challenge-bash-prompt-path-shortener
_dir_chomp () {
    local IFS=/ c=1 n d
    local p=(${1/#$HOME/\~}) r=${p[*]}
    local s=${#r}
    while ((s>$2&&c<${#p[*]}-1))
    do
        d=${p[c]}
        n=1;[[ $d = .* ]]&&n=2
        ((s-=${#d}-n))
        p[c++]=${d:0:n}
    done
    echo "${p[*]}"
}

PS1='\[\033[01;34m\]$(_dir_chomp "$(pwd)" 20)\[\033[00m\]\$ '