rtcwake(8)

1rtcwake(8)                 Linux Programmer's Manual                rtcwake(8)
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NAME

6       rtcwake - enter a system sleep state until specified wakeup time
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SYNOPSIS

9       rtcwake [-hvVlua] [-d device] [-m standby_mode] {-t time_t|-s seconds}
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DESCRIPTION

12       This  program  is  used  to  enter a system sleep state until specified
13       wakeup time.
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15       This uses cross-platform Linux  interfaces  to  enter  a  system  sleep
16       state,  and  leave  it no later than a specified time.  It uses any RTC
17       framework driver that supports standard driver model wakeup flags.
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19       This is normally used like the old apmsleep utility,  to  wake  from  a
20       suspend  state  like  ACPI  S1  (standby) or S3 (suspend-to-RAM).  Most
21       platforms can implement those without analogues of BIOS, APM, or ACPI.
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23       On some systems, this can also be used like nvram-wakeup,  waking  from
24       states like ACPI S4 (suspend to disk).  Not all systems have persistent
25       media that are appropriate for such suspend modes.
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27   Options
28       -v | --verbose
29              Be verbose.
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31       -h | --help
32              Display a short help message that shows how to use the program.
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34       -V | --version
35              Displays version information and exists.
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37       -a | --auto
38              Reads the clock mode (whether the hardware clock is set  to  UTC
39              or  local time) from /etc/adjtime. That's the location where the
40              hwclock(8) stores that information.
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42       -l | --local
43              Assumes that the hardware clock is set to local time, regardless
44              of the contents of /etc/adjtime.
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46       -u | --utc
47              Assumes  that  the  hardware clock is set to UTC (Universal Time
48              Coordinated), regardless of the contents of /etc/adjtime.
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50       -d device | --device device
51              Uses device instead of rtc0 as realtime clock.  This  option  is
52              only  relevant  if  your  system  has more than one RTC. You may
53              specify rtc1, rtc2, ... here.
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55       -s seconds | --seconds seconds
56              Sets the wakeup time to seconds in future from now.
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58       -t time_t | --time time_t
59              Sets the wakeup time to the absolute time time_t. time_t is  the
60              time  in  seconds  since  1970-01-01, 00:00 UTC. Use the date(1)
61              tool to convert between human-readable time and time_t.
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63       -m mode | --mode mode
64              Use standby state mode. Valid values are:
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66              standby
67                     ACPI state S1. This state offers  minimal,  though  real,
68                     power savings, while providing a very low-latency transi‐
69                     tion back to a working system. This is the default mode.
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71              mem    ACPI state S3 (Suspend-to-RAM). This state offers signif‐
72                     icant  power  savings  as everything in the system is put
73                     into a low-power  state,  except  for  memory,  which  is
74                     placed in self-refresh mode to retain its contents.
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76              disk   ACPI  state  S4  (Suspend-to-disk). This state offers the
77                     greatest power savings, and  can  be  used  even  in  the
78                     absence  of  low-level platform support for power manage‐
79                     ment. This state operates  similarly  to  Suspend-to-RAM,
80                     but  includes  a final step of writing memory contents to
81                     disk.
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83              off    ACPI  state  S5  (Poweroff).  This  is  done  by  calling
84                     '/sbin/shutdown'.   Not officially supported by ACPI, but
85                     usually working.
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87              no     Don't suspend. The rtcwake command sets RTC  wakeup  time
88                     only.
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90              on     Don't  suspend,  but  read  RTC  device  until alarm time
91                     appears. This mode is useful for debugging.
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NOTES

94       Some PC systems can't currently exit sleep states  such  as  mem  using
95       only  the  kernel  code  accessed  by this driver.  They need help from
96       userspace code to make the framebuffer work again.
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HISTORY

99       The program was posted several times on LKML  and  other  lists  before
100       appearing  in  kernel  commit  message  for Linux 2.6 in the GIT commit
101       87ac84f42a7a580d0dd72ae31d6a5eb4bfe04c6d.
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AVAILABILITY

104       The rtcwake command is part of the util-linux-ng package and is  avail‐
105       able from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
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AUTHOR

108       The  program  was  written  by  David Brownell <dbrownell@users.source‐
109       forge.net> and improved by Bernhard Walle <bwalle@suse.de>.
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COPYRIGHT

112       This is free software.  You may redistribute copies of it   under   the
113       terms      of       the       GNU      General      Public      License
114       <http://www.gnu.org/licenses/gpl.html>.  There is NO WARRANTY,  to  the
115       extent permitted by law.
116