battery_notifier

#!/bin/bash
# battery_notifier
# Checks battery level and sends notifiers when low and discharging

# Copyright (C) 2014-2015 Alexander Swen <alex@swen.nu>

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Alexander Swen
# Private contact: alex@swen.nu

# CHANGELOG:
# 2015-02-15	A.Swen	created.
# 2016-01-24  A.Swen  Added logmessage to warn that beep isn't there.

# INSTALLATION

# > NOTE: Some systems have a desktop notifier `dunst` installed. That's a very
#         basic notifier program. When possible xfce4-notifyd is much prettier

# This script needs three preparationscteps:
# 1. Install notify-send.
# 2. You need to tell cron to run this every now and then.
# like: */10 * * * * [ -x $HOME/bin/battery_notifier ] && $HOME/bin/battery_notifier >> battery_notifier.log 2>&1
# 3. You need to set the DBUS_SESSION_BUS_ADDRESS variable.
# By default cron does not have access to the variable. To remedy this put the
# following script somewhere and call it when the user logs in, For example put
# this in ~/.xprofile:
#
#   [ -d $HOME/.dbus ] || mkdir $HOME/.dbus
#   env | grep DBUS_SESSION_BUS_ADDRESS > $HOME/.dbus/Xdbus
#   echo 'export DBUS_SESSION_BUS_ADDRESS' >> $HOME/.dbus/Xdbus
#   chmod 600 $HOME/.dbus/Xdbus
#
# If beep is installed there will be a beep when capacity is critical.

# SETTINGS
date=$(date +%Y%m%d)
me=$(basename $0)
mydir=$(dirname $0)
warn=25
crit=10
beep=true
beep_freq=100
beep_time=200
beep_times=3


# FUNCTIONS
die () {
  shift
  printf '%s\n' "=====================" >&2
  printf '%s\n' "==== FATAL ERROR ====" >&2
  printf '%s\n\n' "=====================" >&2
  printf '%s\n\n' "$@" >&2
  exit $rc
}

log () { printf '%s %s\n' "$(date +%F' '%T)" "$@"; }
is_int () { return $(test "$1" -eq "$1" > /dev/null 2>&1); }

get_battery_info () {
  status=$(cat /sys/class/power_supply/BAT0/status)
  capacity=$(cat /sys/class/power_supply/BAT0/capacity)
  time_to_empty="$(time_to_empty)"
}

time_to_empty () {
  upower -i /org/freedesktop/UPower/devices/battery_BAT0|awk '/time to empty:/ {print $4" "$5}'
}

time_to_full () {
  upower -i /org/freedesktop/UPower/devices/battery_BAT0|awk '/time to full:/ {print $4" "$5}'
}

notify () {
  log "Trying to warn the user."
  case $1 in
    warn)
      local ttl=60000
      local urgency=normal
      local message=$(cat << EOF_MSG
Batterylevel is $capacity and $status.
Estimated time to empty: $time_to_empty.
EOF_MSG
      )
      [ $beep == true ] && try_beep
      ;;
    crit)
      local ttl=120000
      local urgency=critical
      local message=$(cat << EOF_MSG
Batterylevel is $capacity and $status.
Estimated time to empty: $time_to_empty.
Laptop will go into sleep in 30 seconds!
EOF_MSG
      )
      [ $beep == true ] && try_beep
      ;;
    *) die 4 "You should use 'warn' or 'crit' as \$1 in the notify function.";;
  esac
  notify-send --expire-time=$ttl --urgency=$urgency "Batery Low Warning" "$message"
}

try_beep () {
  if [ -x /usr/bin/beep ];then
    beep -f $beep_freq -l $beep_time -r $beep_times -d 200
  else
    log "Beep not installed."
    return
  fi
}

# SCRIPT
is_int $warn || die 1 "Warn must be an integer."
is_int $crit || die 1 "Crit must be an integer."
[ $warn -lt $crit ] && die 1 "Warn should be greater than crit."

# Cron needs to know where to send the message to.
[ -f $HOME/.dbus/Xdbus ]&& source $HOME/.dbus/Xdbus || die 1 "$HOME/.dbus/Xdbus not found"

# Check if notify-send is installed.
[ -x /usr/bin/notify-send ]||die 2 "Notify-send not installed."

# Check if batteryinfo is available
[ -f /sys/class/power_supply/BAT0/capacity ]||die 2 "Dunno where to find battery info. /sys/class/power_supply/BAT0/capacity not found."

log "Checking batterystatus."
get_battery_info
[ -n "$status" ] || die 3 "Script failed to detect batterystatus."
[ -n "$capacity" ] || die 3 "Script failed to detect batterycapacity."
is_int $capacity || die 3 "Script didn't get an integer from the capacityfile."

if [[ "$status" == "Discharging" ]];then
  log "The battery is $status and at ${capacity}%. Estimated time to empty: $time_to_empty."
  if [[ $capacity -le $crit ]];then
    notify crit
    sleep 30
    /usr/bin/i3lock -ti /home/alex/mug.png -c 000000 &
    sudo /usr/sbin/pm-suspend
  elif [[ $capacity -le $warn ]];then
    notify warn
  fi
else
  log "The battery is $status and at ${capacity}%. Estimated time to full: $(time_to_full)."
fi

# END