RTCWAKE(8) System Administration RTCWAKE(8)

# [NAME](#NAME)

rtcwake - enter a system sleep state until specified wakeup time

# [SYNOPSIS](#SYNOPSIS)

**rtcwake** \[options] \[**-d** *device*] \[**-m** *standby\_mode*] {**-s** *seconds*|**-t** *time\_t*}

# [DESCRIPTION](#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](#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)](/man/os/util-linux/hwclock.8) 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 <time>". The time is in [**ctime**(3)](/man/os/util-linux/ctime.3) 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)](/man/os/util-linux/date.1) 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](#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](#FILES)

*/etc/adjtime*

# [HISTORY](#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](#AUTHORS)

The program was written by *David Brownell* <dbrownell@users.sourceforge.net> and improved by *Bernhard Walle* <bwalle@suse.de>.

# [COPYRIGHT](#COPYRIGHT)

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.

# [SEE ALSO](#SEE_ALSO)

[**adjtime\_config**(5)](/man/os/util-linux/adjtime_config.5), [**hwclock**(8)](/man/os/util-linux/hwclock.8), [**date**(1)](/man/os/util-linux/date.1)

# [REPORTING BUGS](#REPORTING_BUGS)

For bug reports, use the *issue tracker* <https://github.com/util-linux/util-linux/issues>.

# [AVAILABILITY](#AVAILABILITY)

The **rtcwake** command is part of the util-linux package which can be downloaded from *Linux Kernel Archive* <https://www.kernel.org/pub/linux/utils/util-linux/>.

2026-10-30 util-linux 2.42.4

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Document: rtcwake(8) from util-linux 2.42.4-r2 (Chainguard OS)