- Show whether an alarm is set or not:
sudo rtcwake -m show -v
- Suspend to ram and wakeup after 10 seconds:
sudo rtcwake -m mem -s 
- Suspend to disk (higher power saving) and wakeup 15 minutes later:
sudo rtcwake -m disk --date +min
- Freeze the system (more efficent than suspend-to-ram but linux > 3.9 required) and wakeup at a given date and time:
sudo rtcwake -m freeze --date [YYYYMMDDhhmm]
- Disable a previously set alarm:
sudo rtc -m disable
- Perform a dry run to wakup the computer at a given time. (Press Ctrl + C to abort):
sudo rtcwake -m on --date [hh:ss]
This program is used to enter a system sleep state and to automatically wake from it at a specified time.
This uses cross-platform Linux interfaces to enter a system sleep state, and leave it no later than a specified time. It uses any RTC framework driver that supports standard driver model wakeup flags.
This is normally used like the old apmsleep utility, to wake from a suspend state like ACPI S1 (standby) or S3 (suspend-to-RAM). Most platforms can implement those without analogues of BIOS, APM, or ACPI.
On some systems, this can also be used like nvram-wakeup, waking from states like ACPI S4 (suspend to disk). Not all systems have persistent media that are appropriate for such suspend modes.
Note that alarm functionality depends on hardware; not every RTC is able to setup an alarm up to 24 hours in the future.
This is free software. You may redistribute copies of it under the terms of the GNU General Public License <http://www.gnu.org/licenses/gpl.html>. There is NO WARRANTY, to the extent permitted by law.