bionic (8) rtcwake.8.gz

Provided by: util-linux_2.31.1-0.4ubuntu3.7_amd64 bug

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.

       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>.

       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/⟩.