Difference between revisions of "Display Power Management Signaling"

Revision as of 13:29, 28 October 2012

DPMS (Display Power Management Signaling) is a technology that allows power saving behaviour of monitors when the computer is not in use.

Setting up DPMS in X

Add the following to your /etc/X11/xorg.conf in the Monitor section:

Option "DPMS" "true"

Add the following to the ServerLayout section, change the times (in minutes) as necessary:

Option "StandbyTime" "10"
Option "SuspendTime" "20"
Option "OffTime" "30"

Option         "BlankTime" "30"

As with newer versions of X it is recommended to use different .conf files instead of a xorg.conf, an example file /etc/X11/xorg.conf.d/10-monitor.conf could look like this.

Section "Monitor"
    Identifier "LVDS0"
    Option "DPMS" "false"
EndSection

Section "ServerLayout"
    Identifier "ServerLayout0"
    Option "BlankTime"  "0"
    Option "StandbyTime" "0"
    Option "SuspendTime" "0"
    Option "OffTime" "0"
EndSection

Modifying DPMS and screensaver settings using xset

It is possible to turn off your monitor using the xset tool. Note if using this command manually in a shell you may need to prefix it with sleep 1; for it to work correctly. For example:

sleep 1; xset dpms force off

To control Energy Star (DPMS) features (a timeout value of zero disables the mode):

xset -dpms Energy Star features off
xset +dpms Energy Star features on
xset dpms [standby [suspend [off]]]     
xset dpms force standby 
xset dpms force suspend 
xset dpms force off 
xset dpms force on  (also implicitly enables DPMS features)

xset screen-saver control

You can use xset to control your screensaver:

xset s [timeout [cycle]]  
xset s default    
xset s on
xset s blank              
xset s noblank    
xset s off
xset s expose             
xset s noexpose
xset s activate           
xset s reset

To see your current settings

$ xset q

...

Screen Saver:
  prefer blanking:  yes    allow exposures:  yes
  timeout:  600    cycle:  600
DPMS (Energy Star):
  Standby: 600    Suspend: 600    Off: 600
  DPMS is Enabled
  Monitor is On

Examples

Turn off DPMS

xset -dpms

Disable screen saver blanking

xset s off

Disable DPMS and prevent screen from blanking

Useful when watching movies or slideshows:

xset -dpms; xset s off

Turn off screen immediately

If you leave your computer, you do not need to wait for the timeout you set that the display turns off. Simply enforce it by using the xset command.

xset dpms force off

Put screen into standby

xset dpms force standby

Put screen into suspend

xset dpms force suspend

Change Blank time from 5 min to 1 hour

xset s 3600 3600

xset display.sh

You could also copy this script:

/usr/local/bin/display.sh

#!/bin/bash
# Small script to set display into standby, suspend or off mode
# 20060301-Joffer

case $1 in
  standby|suspend|off)
    xset dpms force $1
  ;;
  *)
    echo "Usage: $0 standby|suspend|off"
  ;;
esac

Make it executable (chmod u+x /usr/local/bin/display.sh) and just run display.sh off. For the latter to work you need to include /usr/local/bin into your path.

DPMS interaction in a Linux console with setterm

The setterm utility issues terminal recognized escape codes to alter the terminal. Essentially it just writes/echos the terminal sequences to the current terminal device, whether that be in screen, a remote ssh terminal, console mode, serial consoles, etc.

setterm Syntax: (0 disables)

setterm -blank [0-60|force|poke]
setterm -powersave [on|vsync|hsync|powerdown|off]
setterm -powerdown [0-60]

Prevent screen from turning off

You can run this command, and add it to /etc/rc.local:

$ setterm -blank 0 -powerdown 0

Alternatively you can disable console blanking permanently using the following command:

# echo -ne "\033[9;0]" >> /etc/issue

Pipe the output to a cat to see the escapes

$ setterm -powerdown 2>&1 | exec cat -v 2>&1 | sed "s/\\^\\[/\\\\033/g"

Pipe the escapes to any tty (with write/append perms) to modify that terminal

Note the use of >> instead of >. For permission issues using sudo in a script or something, you can use the tee program to append the output of setterm to the tty device, which tty's let appending sometimes but not writing.

$ setterm -powerdown 0 > /dev/tty3

Bash loop to set ttys 0-256

$ for i in {0..256}; do setterm -powerdown 0 >> /dev/tty$i; done; unset i;

Troubleshooting

xset DPMS settings do not work with xscreensaver

xscreensaver uses its own DPMS settings. See the settings for xscreensaver for more information.

xscreensaver DPMS

You can configure xscreensaver's DPMS settings manually by editing your ~/.xscreensaver file as below, or using the xscreensaver-demo gui.

timeout:	1:00:00
cycle:		0:05:00
lock:		False
lockTimeout:	0:00:00
passwdTimeout:	0:00:30
fade:		True
unfade:		False
fadeSeconds:	0:00:03
fadeTicks:	20
dpmsEnabled:	True
dpmsStandby:	2:00:00
dpmsSuspend:	2:00:00
dpmsOff:	4:00:00

See also

• PC Monitor DPMS specification explanation