#recursively find files in current directory that have no extension
for i in $(find . -type f ! -name "*.*"); do
    #guess that extension using file
    extfile=$(file --extension --brief $i)
    #select the first extension in the event file spits something weird (e.g. jpeg/jpe/jfif) 
    extawk=$(echo $extfile | awk -F/ '{print $1}')
    #copy the file to a file appended with the extension guessed from the former commands
    mv $i $i.$extawk
done