wiki/structured/cookbook.bash.percent-encoding.org

Percent encoding in Bash

Percent-encoding is commonly used in URLs. Pretty nice especially when used with spaces.

Based from this implementation. It was modified to be closer to the output from Python urlencode.

function urlencode {
    local msg=$1
    local length="${#1}"

    for (( i = 0; i < length; i++ )); do
        local ch="${msg:i:1}"
        case $ch in
            [a-zA-Z0-9.~_-])
                printf "%c" $ch;;
            ,*)
                printf '%s' "$ch" | xxd -plain -cols 1 | {
                    while read hex; do
                        printf "%%%s" $hex
                    done
                };;
        esac
    done
    printf "\n"
}

urlencode "El Doggo"
urlencode "El Niño"
urlencode "Whoa there, sonny!"

ElDoggo
ElNiÃo
Whoatheresonny

To decode percent-encoded strings:

function urldecode {
    # urldecode <string>

    # Replace all pluses with spaces since it usually represents it in URLs.
    local url_encoded="${1//+/ }"

    # Replace all percent sign with '\x' and print the message with byte interpretation.
    printf '%b\n' "${url_encoded//%/\\x}"
}

urldecode "El%20Doggo"
urldecode "%e9%bd%8b%e8%97%a4%e3%83%bbB%e3%83%bb%e6%a5%b5%e3%83%bb%e5%b0%86%e5%97%a3"

El Doggo
齋藤・ B ・極・将嗣