rtcwake(8) — Linux manual page


RTCWAKE(8)                System Administration               RTCWAKE(8)

NAME         top

       rtcwake - enter a system sleep state until specified wakeup time

SYNOPSIS         top

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

DESCRIPTION         top

       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

       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.

OPTIONS         top

       -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) stores
           that information. This is the default.

       --date timestamp
           Set the wakeup time to the value of the timestamp. Format of
           the timestamp can be any of the following:
       │                     │                         │
       │ YYYYMMDDhhmmss      │                         │
       │                     │                         │
       │ YYYY-MM-DD hh:mm:ss │                         │
       │                     │                         │
       │ YYYY-MM-DD hh:mm    │ (seconds will be set to │
       │                     │ 00)                     │
       │                     │                         │
       │ YYYY-MM-DD          │ (time will be set to    │
       │                     │ 00:00:00)               │
       │                     │                         │
       │ hh:mm:ss            │ (date will be set to    │
       │                     │ today)                  │
       │                     │                         │
       │ hh:mm               │ (date will be set to    │
       │                     │ today, seconds to 00)   │
       │                     │                         │
       │ tomorrow            │ (time is set to         │
       │                     │ 00:00:00)               │
       │                     │                         │
       │ +5min               │                         │

       -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 available --mode option arguments.

       -m, --mode mode
           Go into the given standby state. Valid values for mode are:

               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

               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.)

               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.

               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.

               ACPI state S5 (Poweroff). This is done by calling
               '/sbin/shutdown'. Not officially supported by ACPI, but
               it usually works.

               Don’t suspend, only set the RTC wakeup time.

               Don’t suspend, but read the RTC device until an alarm
               time appears. This mode is useful for debugging.

               Disable a previously set alarm.

               Print alarm information in format: "alarm: off|on
               <time>". The time is in ctime() 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) tool to convert between human-readable time and

       -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
           Print version and exit.

NOTES         top

       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         top


HISTORY         top

       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         top

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

COPYRIGHT         top

       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         top

       adjtime_config(5), hwclock(8), date(1)

REPORTING BUGS         top

       For bug reports, use the issue tracker at

AVAILABILITY         top

       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/>. This page
       is part of the util-linux (a random collection of Linux
       utilities) project. Information about the project can be found at
       ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have
       a bug report for this manual page, send it to
       util-linux@vger.kernel.org. This page was obtained from the
       project's upstream Git repository
       ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
       2023-12-22. (At that time, the date of the most recent commit
       that was found in the repository was 2023-12-14.) If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page,
       or you have corrections or improvements to the information in
       this COLOPHON (which is not part of the original manual page),
       send a mail to man-pages@man7.org

util-linux 2.39.594-1e0ad      2023-07-19                     RTCWAKE(8)

Pages that refer to this page: adjtime_config(5)hwclock(8)