I have an Ubuntu server running xdm with openbox on which is plugged a monitor that displays a video which is launched via a cron daemon.

When the monitor is not used for a certain amount of time, it goes into sleep mode and I cannot wake it up with the video process : The monitor stays black.

How can I wake the monitor? Without installing packages if possible, and without a physical access to the machine.

xset --help

usage:  xset [-display host:dpy] option ...

    To control Energy Star (DPMS) features:
    -dpms      Energy Star features off
    +dpms      Energy Star features on
     dpms [standby [suspend [off]]]
          force standby
          force suspend
          force off
          force on
          (also implicitly enables DPMS features)
          a timeout value of zero disables the mode

So if you get the ${DISPLAY} of the monitor you can:

xset -display ${DISPLAY} dpms force on
  • What if I do it via ssh? – Deer Hunter Apr 15 '14 at 13:48
  • @DeerHunter Then you use the display number. – mikeserv Apr 15 '14 at 13:49
  • it works (without the need to specify the display (I have only one)). Thanks ! – Jav Apr 15 '14 at 13:50
  • @Jav - I'm glad to hear it. – mikeserv Apr 15 '14 at 14:00
  • 2
    xset -display :0 dpms force on works for me when I log in via ssh – mixtly87 Oct 20 '19 at 21:45

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