I'm backing up an old hard drive and copying about 300GB of files. It had about 50GB left when I got a kernel panic and now I want to resume the copying. Is there a way to do this in Ubuntu? (A don't copy if file already exists but copy all files that don't already exist argument?)
rsync usually only copies what's missing or changed, there seem to be also some GUIs for it.
The command for you might look like as follows, copying recursively and preserving permissions, timestamps etc. (archive), verbose output, use compression (zip) during transfer, showing Progress:
What did you start the copy operation with?
Nautilus gives you this option:
Hit the 'apply this action to all files' and it will skip all that has already been copied.
But it does depend on how you copy the files.
You can use a synchronization software like freefilesync to compare the folders (by file content), and finish the transfer by setting up the appropriate synchronisation configurations.
Look here on how to install freefilesync.
You can also try "conduit" from the official repositories, but this I have never tried.