rtcwake

(8)

enter a system sleep state until specified wakeup time

Administration and privileged commands 14 optionsutil-linux 2.41-5

rtcwake [options] [-d device] [-m standby_mode] {-s seconds|-t time_t}

Options

-A--adjfilefile

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) stores that information. This is the default.

--datetimestamp

Set the wakeup time to the value of the timestamp. Format of the timestamp can be any of the following:

-d--devicedevice

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--modemode

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 pow

-n--dry-run

This option does everything apart from actually setting up the alarm, suspending the system, or waiting for the alarm.

-s--secondsseconds

Set the wakeup time to seconds in the future from now.

-t--timetime_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) 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.

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 setup 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.

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 dbrownell@users.sourceforge.net and improved by Bernhard Walle bwalle@suse.de.

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.

REPORTING BUGS

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

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/.