screen sessions lost after ssh exit about meta-intel-edison

[htot]

I am on thud. I just tested this by doing screen /dev/ttyS1 115200 and have no problem reconnecting.
Same when just doing screen. Maybe the problem is sumo specific?

[ochrin]

Thanks for testing. I will switch on Thud.

[sideralis]

I switched to Thud, but the problem is also here. I think I was not clear in my problem description so here it is:

• From your desktop or laptop PC, connect to edison through ssh: ssh 192.168.1.xx
• From edison open a screen session: screen, then launch top or htop
• From edison, detach from screen: Ctrl A + D
• From edison, exit from ssh: exit
• From laptop or desktop, reconnect to edison: ssh 192.168.1.xx
• From edison, screen -r should reconnect you to your previous and you should see top still displaying data.
  Unfortunately, this does not work.
  Never mind, I will investigate and come back if I found the issue.

NB: Ochrin = Sideralis :)

[htot]

@sideralis no you were perfectly clear. I just tried again following exactly your steps (pressing crtl D instead of typing exit) and it just works (htop).

Looks like you found an interesting bug. The only real difference I see is I connect ssh [email protected]. Is is possible you created a user account, allowing you to connect ssh 192.168.1.xx?

[sideralis]

Yes, I created some user accounts.
And I confirm your try: if I 'ssh' to root account (ssh [email protected]) then screen session is not lost. If I 'ssh' to user account, screen session is lost.
I will try to investigate...

[htot]

I can reproduce your case. Also:

• if you have 2 terminals open to edison
• create screen and detach in one terminal as non-root
• reattach in 2nd terminal and then close first terminal
• screen in 2nd terminal terminates

No idea why.

[htot]

@sideralis it's a systemd thingy. Read more here and here (Orphaned processes).
Thanks @wdehoog!

What should work (but I didn't try): KillUserProcesses=no in /etc/systemd/logind.conf

or

compile systemd with --without-kill-user-processes

What certainly does work (I tested):

loginctl user-status
sudo loginctl enable-linger ferry
systemd-run --scope --user screen

So it seems to be intended behavior.

[htot]

If you are looking for a recipe that drops a config fragment to modify logind.conf have a look at the pwr-button-handler after this commit:
htot@e07328c

[sideralis]

Thanks for these details.
I modified /etc/systemd/logind.conf on the target and screen is working as expected.
I will have a look at your commit.
Thanks again.

[htot]

You're welcome. Maybe we should add a topic to the documentation in combination with a patch to enable lingering? In the meanwhile I think we can close this issue?

[sideralis]

Yes, we can close.
I am not too familiar with Yocto but I will try to submit a patch for this issue (not right now but in a few weeks).