Code challenge: Bash prompt path shortener

Question

I implemented a prompt path shortener for bash to be included in the PS1 environment variable, which shortens the working directory into something more compact but still descrip

Answer 1

This one is 20 or so characters shorter than my other answer:

_dir_chomp () {
    local p=${1/#$HOME/\~} b s
    s=${#p}
    while [[ $p != "${p//\/}" ]]&&(($s>$2))
    do
        p=${p#/}
        [[ $p =~ \.?. ]]
        b=$b/${BASH_REMATCH[0]}
        p=${p#*/}
        ((s=${#b}+${#p}))
    done
    echo ${b/\/~/\~}${b+/}$p
}