add new line to end of file
Spawn backup script as a separate process
so that the uDev add script completes and exits.
Add basic logging
Delete source files when rsync successfully completes
(rsync should delete files anyway, but sometimes if it was unterrupted the --remove-source-files option can leave some files lying around)
Restart udev once scripts have been updated
Forces udev rules to be re-read.
Make sure backup script is executable
Remove the upgrade script after it has run, to avoid running it twice.
We do not need to use the --update option