My Android mobile phone runs MicroG's LineageOS 14.1 version, and I wanted to add a gamepad controller configuration file onto the phone's system partition.
root?
The system partition is only writable by the root user, but LineageOS by default does not have the su binary installed - you need to download it separately.
The LineageOS' developer settings also have a "root access" setting that has only two options:
- Deactivated
- ADB only
But how to you get root access with adb? It turns out that there is a direct command for it:
$ adb root
$ adb shell
$ whoami
root
read-only filesystem
After becoming root, I wanted to move the key layout file to the correct place:
$ adb push Vendor_2836_Product_0001.kl /sdcard/ $ adb shell $ mv /sdcard/Vendor_2836_Product_0001.kl /system/usr/keylayout/ Error: read only filesystem
The /system partition is mounted as read-only, and I had to re-mount it as read/write:
$ adb root $ adb shell $ mount -o rw,remount /system $ mv /sdcard/Vendor_2836_Product_0001.kl /system/usr/keylayout/ # .. success
Afterwards I changed owner, group and permissions of my file to be the same as those of the other files in the keylayout directory.