Make Tar update existing archives only if present

Question

So i have this one-liner i used:

find . -maxdepth 1 -mindepth 1 -type d -exec tar cvf {}.tar {} --remove-files \;

Where it tar each top directory into their own tar archive, while deleting files after.

Now when it accidentally stop, for whatever reasons, how can i make it continue again? Without recreating the tar when it already exist.

I'm aware of the --update flag, but to my knowledge:

 -u, --update
       only append files newer than copy in archive

Seems to only update if the file is newer, and doesn't really add files when they're not there.

How can i do what i mentioned above, using Bash/Unix tools?

Answer 1

Use r (append mode) instead of c:

find . -maxdepth 1 -mindepth 1 -type d -exec tar rvf {}.tar {} --remove-files \;

This will create an archive if it doesn’t already exist, and append to it if it does.