wecker

#!/usr/bin/env bash
#
# wecker
#
# Use your computer as an alarm clock
#
# Author: Emanuel Duss
#

NOW=`date +%s`

PrintUsage() {
  echo "Usage:
  wecker option <params>

  Options:
    set <time>
      Set the alarm at <time>
    sleep <minutes>
      Suspend the computer after <minutes>
    disable
      Disable the alarm
    status
      Shows the current alarm time

  Examples:
    wecker set 23:00
      The computer will start at 23:00h
    wecker sleep 42m
      The computer will suspend in 42 minutes
    wecker disable
      The computer will not start automatically"
}

case "$1" in
  "set")
    if [ "$UID" -ne 0 ]
    then
      echo "Only root can set the alarm"
      exit 1
    fi
    if [ -z "$2" ]
    then
      echo "You must specify the time (eg. 23:05)!"
      exit 1
    fi
    if ! date -d $2 >/dev/null 2>&1
    then
      echo "Alarm time is invalid."
      exit 1
    fi
    # Alarm only possible in the future
    if [ "`date -d $2 +%s`" -gt "$NOW" ]
    then
      echo "Set alarm for today"
      ALARMTIME="`date -d $2 +%s`"
    elif [ "$((`date -d $2 +%s` - $NOW))" -ge 86400 ]
    then
      echo "Alarm time not possible."
      exit 1
    else
      echo "Set alarm for tomorrow"
      ALARMTIME="$((`date -d $2 +%s` + 86400))"
    fi
    if rtcwake -m no -t "$ALARMTIME" >/dev/null 2>&1
    then
      $0 status
    else
      echo "Alarm set failed!"
      exit 1
    fi
    ;;

  "sleep")
    if [ "$UID" -eq 0 ] && which pm-suspend >/dev/null 2>&1
    then
      SUSPENDCMD="pm-suspend"
    fi
    if which systemctl >/dev/null 2>&1
    then
      SUSPENDCMD="systemctl suspend"
    fi
    if [ -z "$SUSPENDCMD" ]
    then
      echo "Your computer is not able to suspend."
      echo "Please check permissions or install required software."
      exit 1
    fi

    if [ -z "$2" ]
    then
      echo "You must specify how many minutes for sleeping in"
      exit 1
    fi
    if ! [[ "$2" =~ ^[0-9]+$ ]]
    then
      echo "This is not a number."
      exit 1
    fi

    echo "Computer will standby in $2 minutes."
    sleep ${2}m
    $SUSPENDCMD
    ;;

  "status")
    echo -n "Current status: "
    if [ "`awk '/alarm_IRQ/{ print $3 }' /proc/driver/rtc`" == "yes" ]
    then
      ALARM=`cat /sys/class/rtc/rtc0/wakealarm`
      date -d @"$ALARM" "+Alarm is set: %A %Y-%m-%d %H:%M:%S"

      DIFF=`expr $ALARM - $NOW`
      HRS=`expr $DIFF / 60 / 60`
      MINS=`expr \( $DIFF - $HRS \* 60 \* 60 \) / 60`
      echo "Alarm will start in $HRS h $MINS m"
    else
      echo "Alarm is not set."
    fi
    ;;

  "disable")
    if [ "$UID" -ne 0 ]
    then
      echo "Only root can disable the alarm."
      exit 1
    fi
    echo "Disable alarm."
    rtcwake -m disable
    $0 status
    ;;

  "-h")
    PrintUsage
    ;;
  *)
    PrintUsage
    exit 1
    ;;
esac