Sorry, it’s not what I’m asking about. I’ve updated my other post which also explains.
No access to SD Card, USB, nothing once the devices are installed in the field.
I can only work on them using remote software commands.
From that post;
My problem is, once these devices are out in the field, I will not have remote access to them anymore, no way to connect an SD Card or mount USB/Network yet I will need to upgrade the operating systems from remote.
I cannot allow the devices to get software updates in case that breaks something so the only thing we can do is keep updating our own build, and when that is ready, find a way to upgrade the remote devices.
Unlike OpenWrt where I can download the new image onto the device /tmp then use sysupgrade or mtd, how could it be done on these and while running Ubuntu? Meaning, in-place updates.