rtcwake

Enter a system sleep state until specified wakeup time relative to your BIOS clock. More information: https://manned.org/rtcwake.

• 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 10

• Suspend to disk (higher power saving) and wakeup 15 minutes later:

sudo rtcwake -m disk --date +15min

• Freeze the system (more efficient than suspend-to-RAM but version 3.9 or newer of the Linux kernel is required) and wakeup at a given date and time:

sudo rtcwake -m freeze --date YYYYMMDDhhmm

• Disable a previously set alarm:

sudo rtcwake -m disable

• Perform a dry run to wakeup the computer at a given time. (Press Ctrl + C to abort):

sudo rtcwake -m on --date hh:ss