Temporarily prevent linux from shutting down

Question

I have a backup script that runs in the background daily on my linux (Fedora 9) computer. If the computer is shut down while the backup is in progress the backup may be dama

Answer 1

There is molly-guard to prevent accidental shutdows, reboots etc. until all required conditions are met -- conditions can be self-defined.

As already suggested you can as well perform backup operations as part of the shutdown process. See for example this page.