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 [-hvVluan] [-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       -n | --dry-run
38              This option does everything but actually  setup  alarm,  suspend
39              system or wait for the alarm.
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41       -a | --auto
42              Reads  the  clock mode (whether the hardware clock is set to UTC
43              or local time) from /etc/adjtime. That's the location where  the
44              hwclock(8) stores that information. This is the default.
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46       -l | --local
47              Assumes that the hardware clock is set to local time, regardless
48              of the contents of /etc/adjtime.
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50       -u | --utc
51              Assumes that the hardware clock is set to  UTC  (Universal  Time
52              Coordinated), regardless of the contents of /etc/adjtime.
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54       -d device | --device device
55              Uses  device  instead  of rtc0 as realtime clock. This option is
56              only relevant if your system has more  than  one  RTC.  You  may
57              specify rtc1, rtc2, ... here.
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59       -s seconds | --seconds seconds
60              Sets the wakeup time to seconds in future from now.
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62       -t time_t | --time time_t
63              Sets  the wakeup time to the absolute time time_t. time_t is the
64              time in seconds since 1970-01-01, 00:00  UTC.  Use  the  date(1)
65              tool to convert between human-readable time and time_t.
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67       -m mode | --mode mode
68              Use standby state mode. Valid values are:
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70              standby
71                     ACPI  state  S1.  This state offers minimal, though real,
72                     power savings, while providing a very low-latency transi‐
73                     tion back to a working system. This is the default mode.
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75              mem    ACPI state S3 (Suspend-to-RAM). This state offers signif‐
76                     icant power savings as everything in the  system  is  put
77                     into  a  low-power  state,  except  for  memory, which is
78                     placed in self-refresh mode to retain its contents.
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80              disk   ACPI state S4 (Suspend-to-disk). This  state  offers  the
81                     greatest  power  savings,  and  can  be  used even in the
82                     absence of low-level platform support for  power  manage‐
83                     ment.  This  state  operates similarly to Suspend-to-RAM,
84                     but includes a final step of writing memory  contents  to
85                     disk.
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87              off    ACPI  state  S5  (Poweroff).  This  is  done  by  calling
88                     '/sbin/shutdown'.  Not officially supported by ACPI,  but
89                     usually working.
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91              no     Don't  suspend.  The rtcwake command sets RTC wakeup time
92                     only.
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94              on     Don't suspend, but  read  RTC  device  until  alarm  time
95                     appears. This mode is useful for debugging.
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97              disable
98                     Disable previously set alarm.
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NOTES

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

106       The  program  was  posted  several times on LKML and other lists before
107       appearing in kernel commit message for Linux  2.6  in  the  GIT  commit
108       87ac84f42a7a580d0dd72ae31d6a5eb4bfe04c6d.
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AVAILABILITY

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

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

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