Using the following command, I managed to enable multi-user mode in an Android device that doesn't officicially support it:
adb shell setprop fw.max_users 4. For good measure I also added the following entry to the build.prop file:
There's now a Settings menu for creating additional users in my device. Upon creating a new user, I would be switched to the multi-user lock screen with icons at the bottom showing the user accounts available in the device. From there I can choose my user log-in.
Moreover, the account data of the new user survives a reboot. From this, I can conclude that multi-user mode is working.
The problem is my Android device, a media player running some version of Jellybean 4.2, normally doesn't display the lock screen. No lock screen appears when I start up the device nor after I suspend or put the device to sleep.
In fact, the only time I see the lock screen is immediately after creating a new user. Once I've logged in as the new user, I can't switch back to the lock screen because the device is configured to show only the bottom panel and therefore I have no way to click the User icon in the Quick Settings menu of the missing top panel.
It seems a bit overkill to do some low-level system hacks just to achieve the desktop Linux equivalent of Control-Alt-F8, etc. Is there a command, perhaps using some intent or activity available via the Android activity manager tool (am) that would allow me to switch between different user log-ins or at least to switch to the lock screen that would allow me to log in as a different user?