trusty (8) rtcwake.8.gz

NAME

       rtcwake - enter a system sleep state until specified wakeup time

SYNOPSIS

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

DESCRIPTION

       This program is used to enter a system sleep state until specified wakeup 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
       -v | --verbose
              Be verbose.

       -h | --help
              Display a short help message that shows how to use the program.

       -V | --version
              Displays version information and exists.

       -n | --dry-run
              This option does everything but actually setup alarm, suspend system or wait for the alarm.

       -a | --auto
              Reads the clock mode (whether the hardware clock is set to UTC or local time)  from  /etc/adjtime.
              That's the location where the hwclock(8) stores that information. This is the default.

       -l | --local
              Assumes that the hardware clock is set to local time, regardless of the contents of /etc/adjtime.

       -u | --utc
              Assumes  that  the  hardware  clock  is set to UTC (Universal Time Coordinated), regardless of the
              contents of /etc/adjtime.

       -d device | --device device
              Uses 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.

       -s seconds | --seconds seconds
              Sets the wakeup time to seconds in future from now.

       -t time_t | --time time_t
              Sets  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.

       -m mode | --mode mode
              Use standby state mode. Valid values 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.

              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 usually working.

              no     Don't suspend. The rtcwake command sets RTC wakeup time only.

              on     Don't  suspend,  but  read  RTC  device  until  alarm time appears. This mode is useful for
                     debugging.

              disable
                     Disable 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".

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.

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.

AVAILABILITY

       The    rtcwake    command    is    part    of    the   util-linux   package   and   is   available   from
       ftp://ftp.kernel.org/pub/linux/utils/util-linux/.

AUTHOR

       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)