Run scripts before and after updates

It is possible to add pre- and post-update-hooks to the update.sh script that upgrades your whole mailcow installation.

To do so, just add the corresponding bash script into your mailcow root directory:

• pre_update_hook.sh for commands that should run before the update
• post_update_hook.sh for commands that should run after the update is completed

Keep in mind that pre_update_hook.sh runs every time you call update.sh and post_update_hook.sh will only run if the update was successful and the script doesn't have to be re-run.

The scripts will be run by bash, an interpreter (e.g. #!/bin/bash) as well as an execute permission flag ("+x") are not required.