/usr/lib/pm-utils/sleep.d/90clock

90clock.sh

#!/bin/sh

# For older motherboards where setting the clock means you'll turn off the wakeup timer/alarm.
# Such as the Asus M2NPV-VM.
# Useful for MythTV's `mythshutdown` trying to start your video recording computer on time.

# How to set this up on Ubuntu 22.04:
# sudo dpkg-divert --add --rename --local /usr/lib/pm-utils/sleep.d/90clock
# vi /usr/lib/pm-utils/sleep.d/90clock

. "${PM_FUNCTIONS}"

RTC_WAKE=/sys/class/rtc/rtc0/wakealarm

save_alarm() {
    [ -w "$RTC_WAKE" ] || return 0
    cat "$RTC_WAKE" 2>/dev/null
}

restore_alarm() {
    ts="$1"
    case "$ts" in
        ''|0|*[!0-9]*) return 0 ;;
    esac
    [ -w "$RTC_WAKE" ] || return 0
    echo 0 > "$RTC_WAKE"
    echo "$ts" > "$RTC_WAKE"
    sleep 1
    echo "$ts" > "$RTC_WAKE"
}

is_set "$NEED_CLOCK_SYNC" || exit $NA

case "$1" in
  hibernate|suspend)
    ALARM="$(save_alarm)"
    /sbin/hwclock --systohc >/dev/null 2>&1
    restore_alarm "$ALARM"
    exit 0
    ;;
  thaw|resume)
    /sbin/hwclock --hctosys >/dev/null 2>&1
    exit 0
    ;;
  *) exit $NA ;;
esac