archlinux's basedir aware `which`

pathlookup.sh

pathlookup() {
    # a basedir aware 'type -P' (or which) for executables
    #   $1: binary to find

    local path=
    local -a paths=

    IFS=: read -r -a paths <<< "$PATH"

    for path in "${paths[@]}"; do
        [[ ${path:0:1} = [.~] ]] && continue
        if [[ -x $BASEDIR$path/$1 ]]; then
            printf '%s' "$BASEDIR$path/$1"
            return 0
        fi
    done

    return 1
}