wakeat

#!/bin/sh

# Fernando Carmona Varo <ferkiwi@gmail.com

#----
# Sets the computer in suspension (to memory)
# and sets it to automatically wake up at the given time.
#----


[ -z "$1" ] && {
    echo "usage: ${0##*/} <time>"
    exit
}

etime=$(date -d "$@" +%s)
time=$(date -d "$@" +"%D %T")

[ -z $etime ] && exit


echo "Going to sleep! the system will wake aproximately at ${time}."
echo "Press any key to continue, Ctr-C to abort."
read p

now=$(date -d "now" +%s)
if [ $etime -lt $now ]
then
	echo "Please provide a time that is not in the past! (current date: $(date '+%D %T'))"
	exit 1
elif [ $((etime - now)) -lt $((4 * 60)) ]
then
	echo "The waking time might have a short window to be triggered in some systems."
	echo "This means the waking time might be earlier than the one specified by a few minutes."
	echo "Please choose an interval of at least 4 minutes into the future to prevent issues."
	exit 1
fi

[ -w /sys/power/state ] || {
    echo "/sys/power/state: not writable, sudoing"
    cmd="sudo"
}

$cmd rtcwake -m "${MODE:-mem}" -vt ${etime}