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How can I restart x-server from the command line?

I'd really like to be able to restart my gui without having to do a full system reboot.

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7 Answers 7

up vote 105 down vote accepted

First find which display manager your ubuntu is having with following command:

cat /etc/X11/default-display-manager

Than depending on what display manager, you can use one of the following commands:

  • Default Ubuntu (with LightDM)

    sudo restart lightdm  
  • Gnome (with GDM)

    sudo restart gdm
  • KDE (with KDM)

    sudo restart kdm

    Note: From 12.10, Kubuntu also uses LightDM.

  • For MDM (e.g. for Mint Cinnamon)

    sudo restart mdm

Note: on Ubuntu 15.04 run sudo service <name> restart

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This probably changed for Unity. My system cannot find gdm. – Steven Roose Sep 16 '12 at 12:25
AFAIK Unity uses lightdm – txwikinger Mar 25 '14 at 23:51
It seem to close all the applications and documents immediately without saving (unlike regular restart), what's the difference between this and sudo reboot? – uval Feb 1 at 16:23

You can try pressing Ctrl+Alt+Backspace to restart X.

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This is deactivated by default in 10.04 and will therefore normally not work. – Marcel Stimberg Aug 5 '10 at 18:28
It can be reactivated though, by going to System -> Preferences -> Keyboard, clicking the 'Options...' button in the 'Layouts' tab and enabling 'Key sequence to kill the x server'. – dv3500ea Aug 5 '10 at 18:33
The correct shortcut is "Alt+SysRq+k", however he asked for command line. – Li Lo Aug 5 '10 at 20:44

Newest version of Ubuntu as of 24 Oct, 2012.

  1. Open Dash Home
  2. Search for keyboard layout
  3. Click Options
  4. Expand tab labelled "Key sequence to kill the X server"
  5. Enable it and Close.

Command Line:

sudo restart lightdm
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This blog article describes the best way to bind the X server to a key command for those who are looking for that. Not exactly what you asked for, but it provides the same functionality unless you are ssh'ed into another computer. It also works in 12.04 fortunately.

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While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. – Peachy Sep 15 '12 at 11:16

For 11.04 and earlier:

sudo service gdm restart

For 11.10 and later:

sudo service lightdm restart

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+1 Works nicely on the Raspberry Pi as well (in case anyone is curious, that's what got me here :) – Levon Aug 6 '14 at 18:03

Since ubuntu 9.04 Ctrl+Alt+Backspace is disabled, however you can now type Alt gr + Print Screen + K.

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Alt+PrtScr/SysReq+k logged me out pdq and my programs were killed or terminated. Is this the desired behaviour expected when restarting X-server? I have 11.10 and sudo restart lightdm took me into text mode and seemed to stay there shutting down a bunch of daemons then stopping. I had to reboot manually fortunately the off button does it gracefully (sometimes). – Asher Dec 22 '11 at 15:49
SysRq+k kills all running processes and child-processes on the current terminal (i.e. the one running your X-server). Using it may cause the system to lose data! See:… – Stefano Palazzo Dec 22 '11 at 17:50

Found out that you can do sudo pkill X

and it seems to work for me!

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