Linux – Recursive, Non-Overwriting File Copy

cpfile-transferlinux

I've got a directory that contains a bunch of other folders containing CoffeeScript/ JavaScript files. I'm able to compile the CoffeeScript files into a new folder with the same folder structure fine.

What I want to do is copy all the *.js files in the source folder to the destination folder recursively. I also don't want to overwrite any files that are already present in the destination folder. Any thoughts of how to accomplish this?

I tried using cp -n source/**.js desination/ and cp -Rn source/**.js desination/ after looking at another similar question, but it doesn't seem to be working.

Any idea how to accomplish this?

Best Answer

You could use rsync (it also does local copy)

rsync -r --ignore-existing --include=*/ --include=*.js --exclude=* source/ destination
  • -r to recurse into directories,
  • --ignore-existing to ignore existing files in destination,
  • the include and exclude filters mean: include all directories, include all *.js files, exclude the rest; the first include is needed, otherwise the final exclude will also exclude directories before their content is scanned.

Finally, you can add a -P if you want to watch progress, a --list-only if you want to see what it would copy without actually copying, and a -t if you want to preserve the timestamps.

This is not related, but I learned the rsync command recently, when I moved 15 years of documents from one partition to another. Confident that my files were there, I then wiped the old partition and put some other stuff in there; I realized later that I lost all the timestamps, and discovered the -t flag. Just wanted to share my distress :'(

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