Provided by: util-linux_2.34-0.1ubuntu9_amd64 bug


       rtcwake - enter a system sleep state until specified wakeup time


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


       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 terminal to settle down
       before entering a system sleep.


       -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, ...

       -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 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

              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 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 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 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.


       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




       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.


       The program was written by David Brownell <>  and  improved
       by Bernhard Walle <>.


       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.


       hwclock(8), date(1)


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