rtcwake

RTCWAKE(8)                   System Administration                  RTCWAKE(8)

NAME
       rtcwake - enter a system sleep state until specified wakeup time

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

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.

OPTIONS
       -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:

              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-modes
              List available --mode option arguments.

       -m, --mode mode
              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 transi-
                     tion 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 sig-
                     nificant 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  manage-
                     ment.   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
                     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.

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.source-
       forge.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.

SEE ALSO
       hwclock(8), date(1)

AVAILABILITY
       The rtcwake command is part of the util-linux package and is  available
       from  the  Linux  Kernel  Archive <ftp://ftp.kernel.org/pub/linux/utils
       /util-linux/>.

util-linux                         June 2015                        RTCWAKE(8)
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