self extracting archive with bash

simple-archive.sh

#!/bin/bash

if [ "${1::1}" == "/" ]; then
    echo "refusing to archive absolute filenames" >&2
    exit 1
fi

while [ "$1" != "" ]; do
    if [ -d "$1" ]; then
        "$0" "$1"/*
        shift
    else
        if [ "$(dirname $1)" != "." ]; then
            echo "mkdir -p '$(dirname $1)'"
        fi
        
        echo "base64 -d << '+++' | gunzip > '$1'"
        cat "$1" | gzip | base64
        echo +++
        
        shift
    fi
done