xenial (8) rtcwake.8.gz

Provided by: util-linux_2.27.1-6ubuntu3.10_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.

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
       ⟨ftp://ftp.kernel.org/pub/linux/utils/util-linux/⟩.