[Tails-dev] Execute Script on shutdown

Hey folks,

first time here so hello everybody.

I would like Tails to run a script when I am about to shutdown Tails.
The scripts function is to zip, encrypt and copy a file to
a different machine, so a sort of a backup-tool.

Inserting into the rc0 file within /etc did not work and tails
resets the file after reboot/new startup.

What would you suggest how to (automatically) run such a script when
shutting down the system.

Thanks for Tails - appreciate your help a lot