RTCWAKE(8)                            System Administration                            RTCWAKE(8)

       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 ana‐
       logues 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.

       -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 proces‐
                     sors 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 mem‐
                     ory, which is placed in self-refresh mode to retain its contents.

              disk   ACPI state S4 (Suspend-to-disk).  This state offers the greatest power  sav‐
                     ings,  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  


Designed by SanjuD(@ngineerbabu)