Difference between revisions of "Display Power Management Signaling"

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Revision as of 20:38, 6 February 2016

zh-CN:Display Power Management Signaling DPMS (Display Power Management Signaling) enables power saving behaviour of monitors when the computer is not in use. For details on each timeout, see [1]. Note that some monitors make no difference between various DPMS modes.

Setting up DPMS in X

Note: As of Xorg 1.8 DPMS is auto detected and enabled if ACPI is also enabled at kernel runtime.

Add the following to a file in /etc/X11/xorg.conf.d/ 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"
Note: If the "OffTime" option does not work, use screen blanking instead, which will keep the monitor turned on with a black image. Alternatively, change "blanktime" to "0" to disable screen blanking
Option         "BlankTime" "30"

An example file /etc/X11/xorg.conf.d/10-monitor.conf could look like this.

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

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

Modifying DPMS and screensaver settings using xset

It is possible to turn off your monitor using the xset tool which is provided by the xorg-xset package in the official repositories.

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

Example commands:

Command Description
xset s off Disable screen saver blanking
xset s 3600 3600 Change blank time to 1 hour
xset -dpms Turn off DPMS
xset s off -dpms Disable DPMS and prevent screen from blanking
xset dpms force off Turn off screen immediately
xset dpms force standby Standby screen
xset dpms force suspend Suspend screen

To query the 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

See xset for all available commands.

Note: If using xset in xinitrc does not work, specify settings within a file in /etc/X11/xorg.conf.d/. See #Setting up DPMS in X for details.
Warning: XScreenSaver and xfce4-power-manager use their own DPMS settings and override xset configuration. See XScreenSaver#DPMS and blanking settings and Xfce#Display blanking for more information.

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]
Note: If you haven't already read the brief DPMS article linked to below, please skim it to understand how DPMS can be used in the console the same as in X.

Prevent screen from turning off

You can run this command:

$ 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

$ setterm -powerdown 0 >> /dev/tty3
Note: >> is used 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.

Bash loop to set ttys 0-256

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

See also