man cp:
-u, --update
copy only when the SOURCE file is newer than the destination
file or when the destination file is missing
Takze si pravdepodobne postupoval spravne. overit si to mozes napriklad cez prikaz diff, ten ti porovna adresare a vypise v com sa lisia (ake subory mas naviac a ake chybaju, popr. v com sa lisia subory ak su aj aj).