Power management

Systemd

See Systemd (systemd-inhibit).

X11 screensaver

See X11 (screensaver).

Brightness / Backlight

Various way to control laptop screen brightness

• In Ubuntu, open the Brightness & Lock settings applet.
• Use the keyboard Fn keys Fn+Brightness up/down
• Via command-line by editing /sys/class/backlight/intel_backlight (from bug 847001):

cat /sys/class/backlight/intel_backlight/max_brightness
# 976
cat /sys/class/backlight/intel_backlight/brightness
# 123
echo 600 | sudo tee /sys/class/backlight/intel_backlight/brightness
# 600
echo 200 | sudo tee /sys/class/backlight/intel_backlight/brightness
# 200

For ease, use the following script

~/bin/bri (<file name="bri" tag="source">download</file>)

#! /bin/bash

LVL=$1

case $LVL in
    min)
        LVL=200
        ;;
    max)
        LVL=976
        ;;
esac

if (( $LVL <= 976 & $LVL >= 200 )); then
    echo $LVL | sudo tee /sys/class/backlight/intel_backlight/brightness
fi

Add to /etc/sudoers:

joesmith    ALL = NOPASSWD: /usr/bin/tee /sys/class/backlight/intel_backlight/brightness

• Using xbacklight

xbacklight -set 100

• Using setpci. See for example on Samsung NC10 page:

sudo setpci -s 00:02.1 f4.b=77     # where 77 (00-ff) is the brightness value

• On intel cards, try the fix from this page

$ ls /sys/class/backlight/
intel_backlight@

Create a file /usr/share/X11/xorg.conf.d/20-intel.conf with content as shown below, then log off and log back in.

Section "Device"
        Identifier  "card0"
        Driver      "intel"
        Option      "Backlight"  "intel_backlight"
        BusID       "PCI:0:2:0"

EndSection

On some model (e.g. Dell latitude E5430), vendor acpi must be enabled in grub. Edit /etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

Then update grub and reboot:

sudo update-grub