Add file existence checks; forking -> exit; fork for inotifywatch

Add file existence checks; forking -> exit; fork for inotifywatch

- Added checks for file existence before attempting to upload, which can in theory esult in race conditions, but in this case doesn't matter that much.
- Changed forking subroutines to exit instead of return, to prevent forked versions of the script from re-running the same commands
- Changed inotifywatch subroutine to fork