Copying a file only when it is newer than the destination
How do I copy a file in Linux only when the file being copied is newer than the version at the destination?
If the file at the destination is newer, I want the file copy to not go ahead.
Using the update option (-u) with cp should do it for you.
http://beginnerlinuxtutorial.com/help-tutorial/basic-linux-commands/cp-linux-copy-command/
Use rsync
rsync --progress -r -u /from/one/* /to/another/directory