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 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:

              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)

       -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

                     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

                     Disable a previously set alarm.

              show   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

       -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 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.

       -V, --version
              Display version information and exit.

       -h, --help
              Display help text 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

       hwclock(8), date(1)

AVAILABILITY         top

       The rtcwake command is part of the util-linux package and is
       available from the Linux Kernel Archive 

COLOPHON         top

       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
       2021-03-21.  (At that time, the date of the most recent commit
       that was found in the repository was 2021-03-19.)  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                      June 2015                     RTCWAKE(8)

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