#!/bin/bash

download_for_directory() {
    cd $1
    for f in *; do
        if [ -d "$f" ]; then
            download_for_directory $f &
        fi
    done
    ls | cat *.md 2> /dev/null | egrep -o 'https?://[^ ]+' | grep 'pdf' | tr -d ')' | xargs --no-run-if-empty wget --no-clobber --quiet --timeout=5 --tries=2
    
    cd ..
    echo "Done $1"
}

download_for_directory .
wait