Provided by: util-linux_2.31.1-0.4ubuntu3.7_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 maybe 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. In this case is better to use sleep command before invoking suspend by rtcwake.


       -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 timestmap 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 ⟨⟩.