Merge two folders, without overwriting any files

Solution 1:

Not sure why the other answer was deleted, it was almost right.

I use the terminal command to do this:

cp -n -v '/src'/* '/dest'

cp = Copy

-n = Don't overwrite existing

-v = Verbose output

Solution 2:

Depending on the version of macOS you're running, you could just select all the files in AeroFS Backup and drag them into the AeroFS folder. When you do you'll get prompted as below:

If you then tick the Apply to ALL checkbox and click on the Keep Both button, you'll merge the files as you want. (In older versions of macOS you may be prompted with the Merge button instead of the Keep Both button). If you don't get either option, try holding the Option key down as you drag the files across.

IMPORTANT - Before doing this with the folders you want, I would create a couple of test folders (or just make copies of the folders you want to merge) and then test this behaviour, as I'm not sure what versions of macOS originally offered this functionality.