We help IT Professionals succeed at work.
Get Started

gdm issue results in black screen during logging out

Barthax
Barthax asked
on
683 Views
Last Modified: 2013-12-21
Using Ubuntu on a family machine.  The machine remains switched on but may not be logged in.  Family members all have separate profiles + the profiles are logged in & out during the day.  We've noticed that after an indeterminate amount of time, the last person to log out will seem to hang during logging out.  It leaves a black screen with the mouse still active but no interaction is possible as there are no controls available.  I've found that if I send gdm a HUP signal, the problem is resolved (note that I have to do this blind-fold as the tty screens never show up once X is started).  I expect that the hang-up signal to gdm isn't going to be the end solution to fixing the issue so I'm trying to understand why this occurs.

I am lucky to have had an ssh session to the machine on one of these occasions, so at the time I took a "ps -ef | grep gdm" output to give me more insight.  As you can see from the output there are some obviously gdmopen processes which look like they are awaiting input...

Note that this is the second time I have asked this question and the solution I accepted first time has not been a full success:

Historical question: https://www.experts-exchange.com/OS/Unix/X_Windows/Q_23801061.html
Historical answer:
locate gdm.conf on your machine and make sure it has

[daemon]
AlwaysRestartServer=true
root      8678     1  0 Sep29 ?        00:00:00 gdm
root      8693     1  0 Sep29 ?        00:00:00 /usr/lib/gdm/gdmopen -l /bin/sh -c /usr/bin/whiptail --yesno 'There already appears to be an X server running on display :0.  Should another display number be tried?  Answering no will cause GDM to start the server on :0 again.  (You can change consoles by pressing Ctrl-Alt plus a function key, such as Ctrl-Alt-F7 to go to console 7.  X servers usually run on consoles 7 and higher.)' 16 70
peterm   20623  8678  0 08:03 ?        00:00:00 gdm
root     21275 20623  0 08:35 tty16    00:00:14 /usr/bin/X :0 -br -audit 0 -auth /var/lib/gdm/:0.Xauth -nolisten tcp
peterm   22903 22884  0 15:16 pts/0    00:00:00 grep gdm
root     24153     1  0 Oct01 ?        00:00:00 /usr/lib/gdm/gdmopen -l /bin/sh -c /usr/bin/whiptail --yesno 'There already appears to be an X server running on display :0.  Should another display number be tried?  Answering no will cause GDM to start the server on :0 again.  (You can change consoles by pressing Ctrl-Alt plus a function key, such as Ctrl-Alt-F7 to go to console 7.  X servers usually run on consoles 7 and higher.)' 16 70
root     24413     1  0 Oct05 ?        00:00:00 /usr/lib/gdm/gdmopen -l /bin/sh -c /usr/bin/whiptail --yesno 'There already appears to be an X server running on display :0.  Should another display number be tried?  Answering no will cause GDM to start the server on :0 again.  (You can change consoles by pressing Ctrl-Alt plus a function key, such as Ctrl-Alt-F7 to go to console 7.  X servers usually run on consoles 7 and higher.)' 16 70
root     24440     1  0 Oct05 ?        00:00:00 /usr/lib/gdm/gdmopen -l /bin/sh -c /usr/bin/whiptail --yesno 'There already appears to be an X server running on display :0.  Should another display number be tried?  Answering no will cause GDM to start the server on :0 again.  (You can change consoles by pressing Ctrl-Alt plus a function key, such as Ctrl-Alt-F7 to go to console 7.  X servers usually run on consoles 7 and higher.)' 16 70
root     24442 24440  0 Oct05 tty14    00:00:00 /usr/lib/gdm/gdmopen -l /bin/sh -c /usr/bin/whiptail --yesno 'There already appears to be an X server running on display :0.  Should another display number be tried?  Answering no will cause GDM to start the server on :0 again.  (You can change consoles by pressing Ctrl-Alt plus a function key, such as Ctrl-Alt-F7 to go to console 7.  X servers usually run on consoles 7 and higher.)' 16 70

Open in new window

Comment
Watch Question
Top Expert 2015
Commented:
This problem has been solved!
Unlock 1 Answer and 19 Comments.
See Answer
Why Experts Exchange?

Experts Exchange always has the answer, or at the least points me in the correct direction! It is like having another employee that is extremely experienced.

Jim Murphy
Programmer at Smart IT Solutions

When asked, what has been your best career decision?

Deciding to stick with EE.

Mohamed Asif
Technical Department Head

Being involved with EE helped me to grow personally and professionally.

Carl Webster
CTP, Sr Infrastructure Consultant
Ask ANY Question

Connect with Certified Experts to gain insight and support on specific technology challenges including:

  • Troubleshooting
  • Research
  • Professional Opinions
Did You Know?

We've partnered with two important charities to provide clean water and computer science education to those who need it most. READ MORE