--- name: "rtcwake" section: "8" platform: "linux" package: "util-linux" version: "2.42.4-1" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/rtcwake" --- # rtcwake(8) enter a system sleep state until specified wakeup time ## NAME rtcwake - enter a system sleep state until specified wakeup time ## SYNOPSIS **rtcwake** \[options\] \[**-d** *device*\] \[**-m** *standby\_mode*\] {**-s** *seconds*\|**-t** *time\_t*} ## DESCRIPTION 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 set up an alarm up to 24 hours in the future. The suspend setup may be interrupted by active hardware; for example wireless USB input devices that continue to send events for some fraction of a second after the return key is pressed. **rtcwake** tries to avoid this problem and it waits to the terminal to settle down before entering a system sleep. ## OPTIONS - **-A**, **--adjfile** *file* Specify an alternative path to the adjust file. - **-a**, **--auto** Read the clock mode (whether the hardware clock is set to UTC or local time) from the *adjtime* file, where [**hwclock**(8)](/hwclock/8.md) stores that information. This is the default. - **--date** *timestamp* Set the wakeup time to the value of this timestamp. The format of *timestamp* can be any of the following: ``` YYYYMMDDhhmmss "YYYY-MM-DD hh:mm:ss" "YYYY-MM-DD hh:mm" (seconds is 00) YYYY-MM-DD (time is 00:00:00) hh:mm:ss (date is today) hh:mm (date is today, seconds is 00) +number[smhd] (seconds/minutes/hours/days after now) tomorrow (time is 00:00:00) ``` Examples of the **+***number*\[**smhd**\] format are: **+5m**, **+6h**, **+2d**. The unit specifier may be longer: **+5min**, **+6hours**, **+2days**. - **-d**, **--device** *device* Use the specified *device* instead of **rtc0** as realtime clock. This option is only relevant if your system has more than one RTC. You may specify **rtc1**, **rtc2**, ... here. - **-l**, **--local** Assume that the hardware clock is set to local time, regardless of the contents of the *adjtime* file. - **--list-modes** List available **--mode** option arguments. - **-m**, **--mode** *mode* Go into the given standby state. Valid values for *mode* are: **standby** ACPI state S1. This state offers minimal, though real, power savings, while providing a very low-latency transition back to a working system. This is the default mode. **freeze** The processes are frozen, all the devices are suspended and all the processors idled. This state is a general state that does not need any platform-specific support, but it saves less power than Suspend-to-RAM, because the system is still in a running state. (Available since Linux 3.9.) **mem** ACPI state S3 (Suspend-to-RAM). This state offers significant power savings as everything in the system is put into a low-power state, except for memory, which is placed in self-refresh mode to retain its contents. **disk** ACPI state S4 (Suspend-to-disk). This state offers the greatest power savings, and can be used even in the absence of low-level platform support for power management. This state operates similarly to Suspend-to-RAM, but includes a final step of writing memory contents to disk. **off** ACPI state S5 (Poweroff). This is done by calling '/sbin/shutdown'. Not officially supported by ACPI, but it usually works. **no** Don’t suspend, only set the RTC wakeup time. **on** Don’t suspend, but read the RTC device until an alarm time appears. This mode is useful for debugging. **disable** Disable a previously set alarm. **show** Print alarm information in format: "alarm: off\|on \". The time is in [**ctime**(3)](/ctime/3.md) output format, e.g., "alarm: on Tue Nov 16 04:48:45 2010". - **-n**, **--dry-run** This option does everything apart from actually setting up the alarm, suspending the system, or waiting for the alarm. - **-s**, **--seconds** *seconds* Set the wakeup time to *seconds* in the future from now. - **-t**, **--time** *time\_t* Set the wakeup time to the absolute time *time\_t*. *time\_t* is the time in seconds since 1970-01-01, 00:00 UTC. Use the [**date**(1)](/date/1.md) tool to convert between human-readable time and *time\_t*. - **-u**, **--utc** Assume that the hardware clock is set to UTC (Universal Time Coordinated), regardless of the contents of the *adjtime* file. - **-v**, **--verbose** Be verbose. - **-h**, **--help** Display help text and exit. - **-V**, **--version** Display version and exit. ## NOTES Some PC systems can’t currently exit sleep states such as **mem** using only the kernel code accessed by this driver. They need help from userspace code to make the framebuffer work again. ## FILES */etc/adjtime* ## HISTORY The program was posted several times on LKML and other lists before appearing in kernel commit message for Linux 2.6 in the GIT commit 87ac84f42a7a580d0dd72ae31d6a5eb4bfe04c6d. ## AUTHORS The program was written by *David Brownell* \ and improved by *Bernhard Walle* \. ## COPYRIGHT This is free software. You may redistribute copies of it under the terms of the *GNU General Public License* \. There is NO WARRANTY, to the extent permitted by law. ## SEE ALSO [**adjtime\_config**(5)](/adjtime_config/5.md), [**hwclock**(8)](/hwclock/8.md), [**date**(1)](/date/1.md) ## REPORTING BUGS For bug reports, use the *issue tracker* \. ## AVAILABILITY The **rtcwake** command is part of the util-linux package which can be downloaded from *Linux Kernel Archive* \.