By default, batocera.linux is like a firmware. It's a file called /boot/batocera. You cannot modify it directly, and for most use cases, you shouldn't need to modify it. All the user data is stored in /userdata/, which is writable.

That said, in case you need to modify the system, there are tips to do it.

For any modification in /boot:

mount -o remount,rw /boot

For any other modifications, you can directly edit the files in their directory (for example if you want to play with the configgen scripts in /usr/lib/python2.7/site-packages/configgen/generators/). Once the modifications are done, you can save them with the command:

batocera-save-overlay

This script creates a file at /boot/boot/overlay file that stores all the modifications you made.

If you don't use the batocera-save-overlay script, you can still edit the files in /usr/ but any modification will be lost on reboot.

If you want to remove all your customizations, just remove this /boot/boot/overlay file.

Note : it cannot be done for the current Odroid xu4 version.

Some best practices here:

• You generally don't need to edit /etc/fstab, use store_games_on_a_nas instead.
• You should not modify /usr/share/emulationstation/es_systems.cfg. Instead, copy this file to /userdata/system/configs/emulationstation/es_systems.cfg and customize it from there. At startup, EmulationStation prefers the latter file if it exists.