I had a device running Ubuntu 12.04 LTS have its screen freeze. Generally I have simply jumped onto an available tty, i.e. Ctrl-Alt-F1 and executed the command /etc/init.d/lightdm restart or service lightdm restart. This however kills everything I have open. How do I avoid this?
asked Mar 23 '13 at 1:40
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1You can't achieve this. It is lightdm which displays/manages windows in x system. – Apple II Mar 23 '13 at 1:46
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This will also kill whatever you have open, but once upon a time ctrl-alt-backspace would restart X. That's easier than switching to a TTY, logging in, and asking X to restart itself. I'm not sure if it still works though. – user162316 Mar 23 '13 at 3:46
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@Douglas B. Staple - It doesn't work with Ubuntu 12.04 LTS. Not sure whether it still works with other distributions or whether this is specific to Unity. – PeanutsMonkey Mar 23 '13 at 7:11
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There may be some way to replace the window manager while running. (It's possible with the GNOME-Shell at least, or with the i3 window manager so there could be some way). – FSMaxB Mar 24 '13 at 8:51
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@FSMaxB - Could you please elaborate on how this can be achieved using the Gnome-Shell or i3 Window Manager? – PeanutsMonkey Mar 26 '13 at 17:59
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DISCLAIMER: According to Brenden's comment, this might be outdated and not work anymore with newer versions of Ubuntu. Also please be prepared that you might lose your open windows.
Now I got it for Unity (I just replaced my GNOME shell with unity without logging out or closing windows):
- Go to tty1 [Ctrl]+[Alt]+[F1]
- Type in
DISPLAY=:0so that programs know on what port to find the X-Server export DISPLAYunity --replaceorgnome-shell --replace(you can also replace GNOME-Shell by unity or Unity by the GNOME-Shell)
This only works if not the X-Server or GNOME is frozen but only Unity or the GNOME-Shell.
How it works: The communication between programs and the X-Server for displaying their UI is working over a network socket. This normally is at "localhost:0" short ":0". By setting the DISPLAY variable, the programs know where to find the X-Server to communicate with it, so programs are displayed on the X-Server on tty7 even if the program is running on tty1.
The content of windows is managed by the X-Server whereas the position and borders of the windows is managed by the window manager integrated in unity or the GNOM-shell so there is a way to replace only them without restarting the applications on the X-Server.
PS: I'm just describing what I understand it to be, so please edit and correct me if I'm wrong in some points.
EDIT:
For the GNOME-Shell, there is another way to restart it. After changing to tty simply type in pkill -HUP gnome-shell, I don't know if there's something similar for Unity.
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That worked like a miracle. In fact it saved me today. Thanks so much. I would be so grateful if you could elaborate what each of the steps do bar step 1. I don't quite understand what is happening under the hood. – PeanutsMonkey Apr 1 '13 at 4:56
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Thanks for answer! Note unity --help says: "--replace Run unity /!\ This is for compatibility with other desktop interfaces and acts the same as running unity without --replace" – Tom Jul 13 '15 at 19:59
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2--replace is deprecated and does nothing and this solution will restart your session meaning you lose all of your windows :( – Brenden Aug 5 '15 at 15:23
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If your screen is frozen, but mouse is still moving (however no result on left-click) - try
- close suspicious (in terms of locking too much memory) apps;
You can use keyboard alt-tab to select and alt-f4 to close.
- right-click anywhere.
Dunno why it happens and why right-click works, but at least it works.
