I want to change some system apps config (hiawatha, for example) that the changes are preserved after the update.
Is the way for it?
asked
How to create custom config?
Anything stored on the data partition is preserved through upgrades
Any changes you make to the root partition files are lost on a Venus firmware update. You will need to write a script that reapplies any changes. You can call that script from /data/rc.local or /data/rcS.local but make sure it doesn't repeat the work with every boot.
My SetupHelper package, in part, provides a mechanism to reapply changes after a Venus update. You might look at it for ideas.
https://github.com/kwindrem/SetupHelper
/data/rc.local and /data/rcS.local are called during boot by initd. These are shell scripts that can call other scripts or programs. But the program/script must return to allow the boot process to complete.
These are extensions of the traditional rc.local mechanism, placed in /data so they survive a Venus OS firmware update.
Anything that you need to execute and survive a Venus OS update can be called from these scripts.
rcS.local is called early in the boot process before much of the system is still not funcitonal. rc.local is called near the end of the boot process.
Because the root partition (including /etc) are overwritten by a firmware update. So /data/etc is an extension of /etc that DOES survive a firmware update.
There is some information provided by Victron here:
https://www.victronenergy.com/live/ccgx:root_access
