A URL shortening service in bash

shorten.sh

#!/usr/bin/env bash
set -e

B56ALPHABET="ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnpqrstuvwxyz23456789"

if [[ "$REQUEST_METHOD" = "GET" ]]; then
    URL=$(redis-cli get ${PATH_INFO:1})
    if [[ -z "$URL" ]]; then
        echo "Status: 404 Not Found"
        echo "Content-Type: text/plain"
        echo && echo "Not Found: $PATH_INFO"
    else
        echo "Status: 301 Moved Permanently"
        echo "Location: $URL"
    fi
elif [[ "$REQUEST_METHOD" = "POST" ]]; then
    if [[ "$CONTENT_LENGTH" -gt 0 ]]; then
        read -n "$CONTENT_LENGTH" URL <&0
        ID=$(redis-cli incr urls)
        DIGITS=$(echo "obase=56; ibase=10; $ID" | bc)
        for d in $DIGITS; do
            HASH="${B56ALPHABET:$((0+$d)):1}$HASH"
        done
        redis-cli set "$HASH" "$URL" >/dev/null
        echo "Status: 201 Created"
        echo "Location: /$HASH"
        echo && echo "$HASH"
    else
        echo "Status: 400 Bad Request"
        echo "Content-Type: text/plain"
        echo && echo "Must provide a URL and Content-Length header"
    fi
else
    echo "Status: 405 Method Not Allowed"
    echo "Content-Type: text/plain"
    echo && echo "Method $REQUEST_METHOD not allowed"
fi