rtcwake

Show alarm status

$ sudo rtcwake -m show -v

$ sudo rtcwake -m mem -s 10

$ sudo rtcwake -m disk --date +15min

$ sudo rtcwake -m freeze --date [YYYYMMDDhhmm]

$ sudo rtcwake -m disable

$ sudo rtcwake -m on --date [hh:mm]

rtcwake [-m mode] [-s seconds|--date time] [options]

rtcwake enters a system sleep state and configures the RTC (Real-Time Clock) to wake the system at a specified time. It's useful for scheduled tasks, power saving, and automatic system wake.
The tool supports various sleep modes with different power/wake trade-offs. The RTC alarm persists even if the system loses power (battery backup).

-m, --mode _mode_

Sleep/action mode

Wake after N seconds

Wake at specific time

Verbose output

Use specific RTC device

mem

Suspend to RAM (S3)

Suspend to disk/hibernate (S4)

Suspend-to-idle (S0ix, kernel 3.9+)

Power off system

No sleep, just set wakeup time

Display current alarm

Cancel pending alarm

Requires root privileges. Not all hardware supports all modes. Time is relative to hardware clock (usually UTC). BIOS/UEFI must support RTC wake.

rtcwake is part of util-linux, providing a standard interface to the Linux RTC wake functionality used for scheduled wake-ups and automated power management.

systemctl(1), hwclock(8), pm-suspend(8)