Display Power Management Signaling

From ArchWiki

DPMS (Display Power Management Signaling) enables power saving behaviour of monitors when the computer is not in use. The time of inactivity before the monitor enters into a given saving power level, standby, suspend or off, can be set as described in DPMSSetTimeouts(3). Note that DPMS was developed for CRT monitors, and on LCD displays, there is normally no difference between the standby, suspend and off 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 ServerFlags 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"
EndSection

Section "ServerFlags"
    Option "StandbyTime" "0"
    Option "SuspendTime" "0"
    Option "OffTime" "0"
    Option "BlankTime" "0"
EndSection

Section "ServerLayout"
    Identifier "ServerLayout0"
EndSection

Disabling DPMS

Merge-arrows-2.pngThis article or section is a candidate for merging with [[]].Merge-arrows-2.png

Notes: The section above already mentions "DPMS" "false" (Discuss in Talk:Display Power Management Signaling)

Since DPMS is enabled by default in many scenarios, explicit action must be taken to disable it. To completely disable DPMS, add the following to a file in /etc/X11/xorg.conf.d/10-monitor.conf: 

Section "Extensions"
    Option      "DPMS" "Disable"
EndSection

Modify DPMS and screensaver settings with a command

It is possible to turn off your monitor with the xset command which is provided by the xorg-xset package.

Examples:

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(1) for all available commands.

Note:
  • 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.
  • If using the 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
  • xset dpms 0 0 0, which sets all the DPMS timeouts to zero, could be a better way to "disable" DPMS, since the effect of -dpms would be reverted when, for example, turning off the screen with xset dpms force off.
  • 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.

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:
  • Console blanking alone does not enable DPMS power saving. Console blanking is disabled by default. [1]
  • setterm --powerdown does not seem to have any effect when the APM_DISPLAY_BLANK kernel configuration option is not enabled. [2]
  • Console blanking can also be enabled by the consoleblank kernel parameter. See the kernel documentation for details.

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