pure bash abspath

abspath.sh

#!/bin/bash

abspath() {
    local thePath
    if [[ ! "$1" =~ ^/ ]]
    then
        thePath="$PWD/$1"
    else
        thePath="$1"
    fi
    echo "$thePath"|(
        IFS=/
        read -a parr
        declare -a outp
        for i in "${parr[@]}"
        do
            case "$i" in
            ''|.)
                continue
                ;;
            ..)
                len=${#outp[@]}
                if ((len == 0))
                then
                    continue
                else
                    unset outp[$((len-1))] 
                fi
                ;;
            *)
                len=${#outp[@]}
                outp[$len]="$i"
                ;;
            esac
        done
        echo /"${outp[*]}"
    )
}