sleep_critical_power.sh

sleep_critical_power.sh

#!/usr/bin/env bash

# Notifies the user if the battery is low.
# Executes some command (like hibernate) on critical battery.
# This script is supposed to be called from a cron job.

function notify-send() {
    # Detect the name of the display in use
    local display=":$(ls /tmp/.X11-unix/* | sed 's#/tmp/.X11-unix/X##' | head -n 1)"

    # Detect the user using such display
    local user=$(who | grep '('$display')' | awk '{print $1}' | head -n 1)

    # Detect the id of the user
    local uid=$(id -u $user)

    sudo -u $user DISPLAY=$display DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/$uid/bus notify-send "$@"
}

level=$(cat /sys/class/power_supply/BAT0/capacity)
status=$(cat /sys/class/power_supply/BAT0/status)

# Exit if not discharging
if [ "${status}" != "Discharging" ]; then
  exit 0
fi

# Percentage at which to show low-battery notification
low_notif_percentage=20
# Percentage at which to show critical-battery notification
critical_notif_percentage=15
# Percentage at which to power-off
critical_action_percentage=10


if [ "${level}" -le ${critical_action_percentage} ]; then
  # sudo is required when running from cron
  systemctl suspend
  exit 0
fi

if [ "${level}" -le ${critical_notif_percentage} ]; then
  notify-send -i '/usr/share/icons/gnome/256x256/status/battery-caution.png' "Battery critical: ${level}%"
  exit 0
fi

if [ "${level}" -le ${low_notif_percentage} ]; then
  notify-send -i '/usr/share/icons/gnome/256x256/status/battery-low.png' "Battery low: $level%"
  exit 0
fi