# Created on savesnippets.com · https://savesnippets.com/3GE2XCwdcvJygO
urlencode() {
    local s="$1" out=""
    local i c
    for (( i = 0; i < ${#s}; i++ )); do
        c="${s:i:1}"
        case "$c" in
            [a-zA-Z0-9._~-]) out+="$c" ;;
            *) printf -v hex '%%%02X' "'$c"
               out+="$hex" ;;
        esac
    done
    printf '%s' "$out"
}

urldecode() {
    local s="${1//+/ }"
    printf '%b' "${s//%/\\x}"
}

urlencode "hello world & friends"     # hello%20world%20%26%20friends
urldecode "hello%20world%20%26%20friends"   # hello world & friends