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#1 2019-11-28 21:48:03

chomwitt
Member
Registered: 2014-09-12
Posts: 12

What is the command behind the user menu ?

In my top panel , on the left, i have the name of the user.
I dont know how is called more properly.

Anyway , clicking on it open a menu,
- lock screen
- Switch user
- Hibernation
- Close.

Unfortunately to me locking or switching blanks the screen withonly a cursor blinking top left
forcing me to reboot , and then the kernel i guess , fixed some orphaned links to the filesystem.

So it worries me a lot. Because the same happens if i have the automatically lock on after an
idle period xfce power setting. A simple command causing possibly filesystem corruption??

So most propably , my guessing is that it's an nvidia (my gpu card) or xorg issue. Nevertheless searching
it i think it would help me to find what commands exactly are triggered by those menus and the power settings.

Chomwitt.

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#2 2019-11-28 22:05:24

chomwitt
Member
Registered: 2014-09-12
Posts: 12

Re: What is the command behind the user menu ?

I forgot to mention that its a fresh installation of debian 10 with xfce 4.2
and that from the start the switch user entry on the 'user' menu is grayed out.

I'm thinking a test reverting to nouveua gpu drivet to see how it works out.

Last edited by chomwitt (2019-11-28 22:05:36)

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#3 2019-11-30 02:19:13

Skaperen
Member
From: right by Jesus, our Saviour
Registered: 2013-06-15
Posts: 482

Re: What is the command behind the user menu ?

i don't know if there is a specific command.  there is a messaging bus existing that many Xfce tools use as well as many outside of Xfce.  what i am understanding is that a message is sent to lightdm, a daemon that is already running, which carries out more steps to complete the request.  there is a command called "dm-tool" that can send that same message to lightdm, but it does not need to be used to do that.  it would be overkill for program that already connect to this bus to run dm-tool for this purpose.  so, if you want to know what other programs use, the answer could be "nothing".  if you want to know what command can be used to accomplish this (without a bunch of added coding), then the answer is probably "dm-tool".

at least, that's what i understand to be going on.  i could be all wrong.

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#4 2019-11-30 02:34:37

Skaperen
Member
From: right by Jesus, our Saviour
Registered: 2013-06-15
Posts: 482

Re: What is the command behind the user menu ?

among the steps that lightdm performs, if the switch to user target user is not logged in, is to log it in.  at some point before or after having the greeter ask for a password (probably before) it needs to start a new instance of Xorg in the name of that user (though Xorg runs as root).  i suspect your issue is that the new instance of Xorg is failing to start and getting "hung" on something like waiting for the hardware to complete an operation it actually isn't doing because the operation wasn't quite right.  this could be the result of some incorrect state left by the previous instance of Xorg when it was suspended by lightdm (a console switch in the kernel which is the going to black that you see).

Last edited by Skaperen (2019-11-30 02:35:41)

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#5 2019-12-03 22:46:06

chomwitt
Member
Registered: 2014-09-12
Posts: 12

Re: What is the command behind the user menu ?

Skaperen thanks for the feedback and the hints about the what happens in case target user is not logged in.

In my case i still dont understand why the switch option is grayed .

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#6 2019-12-04 09:32:42

chomwitt
Member
Registered: 2014-09-12
Posts: 12

Re: What is the command behind the user menu ?

I set up a virtual qemu machine with debian 10 and xfce 4.12

With only root user on system , switch user menu grayed.
After creating two users again is grayed out.

So for now i assume the reason it the one explained in https://forum.xfce.org/viewtopic.php?id=12039
That is that lightdm dont handle userswitch properly. but gdm does.


Interestengly : $ apt-rdepends xfce4 | grep lightdm   
returns null.
How does xfce4 chooses which display manager to use?

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#7 2019-12-04 13:39:46

ToZ
Moderator
From: Canada
Registered: 2011-06-02
Posts: 6,046

Re: What is the command behind the user menu ?

Have a read through this thread for some background and information on how to re-direct the gdmflexiserver command to use lightdm's user switch functionality.

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#8 2019-12-05 01:12:19

Skaperen
Member
From: right by Jesus, our Saviour
Registered: 2013-06-15
Posts: 482

Re: What is the command behind the user menu ?

maybe we're not trying to do the same thing.  but i do "dm-tool switch-to-user" hundreds of times a day via keyboard shortcuts (directly, not via my stu script) and it works great all the time.  this is xubuntu 18.04.3 LTS upgraded to Dec 3.

lt2a/forums /home/forums 36> fgrep 'dm-tool switch-to-user' .config/xfce4/xfconf/xfce-perchannel-xml/xfce4-keyboard-shortcuts.xml|wc -l
21
lt2a/forums /home/forums 37> head /etc/{debian_version,lsb-release,os-release}
==> /etc/debian_version <==
buster/sid

==> /etc/lsb-release <==
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=18.04
DISTRIB_CODENAME=bionic
DISTRIB_DESCRIPTION="Ubuntu 18.04.3 LTS"

==> /etc/os-release <==
NAME="Ubuntu"
VERSION="18.04.3 LTS (Bionic Beaver)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 18.04.3 LTS"
VERSION_ID="18.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
lt2a/forums /home/forums 38> 

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#9 2019-12-06 22:30:19

chomwitt
Member
Registered: 2014-09-12
Posts: 12

Re: What is the command behind the user menu ?

In my case in the Actions item of the top panel the action 'Switch user' is grayed out.

I tried ToZ's proposal to create my /usr/local/bin/gdmflexiserver script ,
and the action's name is not grayed anymore but executing the command
makes screen dark and my system unresponsive.

#/bin/sh
dm-tool switch-to-user

but in my case also executing
$ dm-tool switch-to-user
or
$ dm-tool lock
makes my system unresponsive presenting to me a blank screen with a cursor blinking top left forcing me to do a soft reboot thus risking my filesystem's stability since when kernel is rebooting it finds and corrects orphaned inodes.

I've also posted  an issue in lightdm's github page

My System:    Kernel: 4.19.0-6-amd64 x86_64 bits: 64 Desktop: Xfce 4.12.4
                     Distro: Debian GNU/Linux 10 (buster)

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#10 2019-12-06 22:49:42

ToZ
Moderator
From: Canada
Registered: 2011-06-02
Posts: 6,046

Re: What is the command behind the user menu ?

Which video card and driver are you using? See https://github.com/the-cavalry/light-locker/issues/114 for an ongoing discussion and some suggestions depending on video card. Either way, this looks like a lightdm issue that you are facing.

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#11 2019-12-07 00:15:30

chomwitt
Member
Registered: 2014-09-12
Posts: 12

Re: What is the command behind the user menu ?

Another aspect of the issue i'am experiencing is that executing:
$ light-locker-command  -l   
will also make my screen black and my system unresposive (*).

I dont understand how lightdm , dm-tool and lightlocker interact.

(*) If i keep ctrl+alt+F2  pressed i see the virtual console login text flashing but i cant type anything.
and ctrl+alt+F7 will present a totally black screen without even the blinking top left cursor.

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#12 2019-12-07 00:16:38

chomwitt
Member
Registered: 2014-09-12
Posts: 12

Re: What is the command behind the user menu ?

ToZ wrote:

Which video card and driver are you using? See https://github.com/the-cavalry/light-locker/issues/114 for an ongoing discussion and some suggestions depending on video card. Either way, this looks like a lightdm issue that you are facing.


CPU: AMD Ryzen 5 2600 (12) @ 3.400GHz
GPU: NVIDIA GeForce GTX 960

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#13 2019-12-07 00:48:15

chomwitt
Member
Registered: 2014-09-12
Posts: 12

Re: What is the command behind the user menu ?

I tried :
$ apt-get purge light-locker    (not being sure what exaclty that package too)
$ apt-get install xscreensaver.

Now the 'Lock Screen' action work ok. Switch user still grayed.
And $ dm-tool lock   
will throw me away in dark.

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#14 2019-12-07 01:45:24

Skaperen
Member
From: right by Jesus, our Saviour
Registered: 2013-06-15
Posts: 482

Re: What is the command behind the user menu ?

did you do dm-tool switch-to-user with or without a user name?  doing that command with a username should login a new user without logging out the previous user.  i would try a delayed switch back to see if it can at least switch back to the working session.  if it can, that might let you do testing without needing to reboot every time.  i would make this script:

#!/bin/bash
echo Here we go.
sleep 3
echo -n 'Now ... '
dm-tool switch-to-user newuser
echo Done.
sleep 3
echo 'See, i am still running in the background while you were on that other user.'
sleep 7
dm-tool switch-to-user olduser
sleep 5
echo 'Kill me with ^C (Ctrl+C) within 30 seconds or else I am going to reboot this computer.'
sleep 3
echo 'Yes I can.  Bet on it.'
sleep 30
sudo reboot
echo "D'oh!"
exit

replace newuser and olduser with the user names you are doing.

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#15 2019-12-07 02:05:48

ToZ
Moderator
From: Canada
Registered: 2011-06-02
Posts: 6,046

Re: What is the command behind the user menu ?

chomwitt wrote:
ToZ wrote:

Which video card and driver are you using? See https://github.com/the-cavalry/light-locker/issues/114 for an ongoing discussion and some suggestions depending on video card. Either way, this looks like a lightdm issue that you are facing.


CPU: AMD Ryzen 5 2600 (12) @ 3.400GHz
GPU: NVIDIA GeForce GTX 960

Delete the gdmflexiserver file you created, then give gdm a try (gdm will install its own gdmflexiserver file). I think this is a bug with lightdm/dm-tool.

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