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 persis-
       tent 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.

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 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 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.sourceforge.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  <https://www.kernel.org/pub/linux
       /utils/util-linux/>.

util-linux							     June 2015								RTCWAKE(8)