url encoding and decoding in bash

url-endecode.sh

#!/bin/bash

url-encode () 
{ 
    if [[ ! -z ${2} || -z ${1} ]]; then
        echo "error: this command needs one and only one value";
        echo "       enclose spaces or special chars with quotes";
        return 1;
    fi;
    local string strlen encoded pos proto c o;
    proto="$(echo ${1} | \grep --color=never :// | sed -e 's#^\(.*://\).*#\1#g')";
    string="${1/${proto}/}";
    strlen=${#string};
    encoded="${proto}";
    for ((pos=0; pos<strlen; pos++))
    do
        c=${string:$pos:1};
        case "${c}" in 
            [-_.~a-zA-Z0-9/])
                o="${c}"
            ;;
            *)
                printf -v o '%%%02x' "'$c"
            ;;
        esac;
        encoded+="${o}";
    done;
    REPLY="${encoded}";
    echo "${REPLY}"
}

url-decode () 
{ 
    printf -v REPLY '%b' "${1//%/\\x}";
    echo "${REPLY}"
}