1RTCWAKE(8)                   System Administration                  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 [options] [-d device] [-m standby_mode] {-s seconds|-t time_t}
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DESCRIPTION

12       This program is used to enter a system sleep state and to automatically
13       wake from it at a specified 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       Note that alarm functionality depends on hardware;  not  every  RTC  is
28       able to setup an alarm up to 24 hours in the future.
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30       The  suspend  setup  may be interrupted by active hardware; for example
31       wireless USB input devices that continue to send events for some  frac‐
32       tion  of  a  second  after the return key is pressed.  rtcwake tries to
33       avoid this problem and it waits  to  terminal  to  settle  down  before
34       entering a system sleep.
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OPTIONS

38       -A, --adjfile file
39              Specify an alternative path to the adjust file.
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41       -a, --auto
42              Read the clock mode (whether the hardware clock is set to UTC or
43              local time) from the adjtime file, where hwclock(8) stores  that
44              information.  This is the default.
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46       --date timestamp
47              Set  the  wakeup  time to the value of the timestamp.  Format of
48              the timestamp can be any of the following:
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50              YYYYMMDDhhmmss
51              YYYY-MM-DD hh:mm:ss
52              YYYY-MM-DD hh:mm     (seconds will be set to 00)
53              YYYY-MM-DD           (time will be set to 00:00:00)
54              hh:mm:ss             (date will be set to today)
55              hh:mm                (date will be set to today, seconds to 00)
56              tomorrow             (time is set to 00:00:00)
57              +5min
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59       -d, --device device
60              Use the specified device instead  of  rtc0  as  realtime  clock.
61              This  option  is  only relevant if your system has more than one
62              RTC.  You may specify rtc1, rtc2, ... here.
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64       -l, --local
65              Assume that the hardware clock is set to local time,  regardless
66              of the contents of the adjtime file.
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68       --list-modes
69              List available --mode option arguments.
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71       -m, --mode mode
72              Go into the given standby state.  Valid values for mode are:
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74              standby
75                     ACPI  state  S1.  This state offers minimal, though real,
76                     power savings, while providing a very low-latency transi‐
77                     tion back to a working system.  This is the default mode.
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79              freeze The  processes  are frozen, all the devices are suspended
80                     and all the processors idled.  This state  is  a  general
81                     state  that  does not need any platform-specific support,
82                     but it saves less power than Suspend-to-RAM, because  the
83                     system  is  still  in  a running state.  (Available since
84                     Linux 3.9.)
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86              mem    ACPI state S3 (Suspend-to-RAM).  This state  offers  sig‐
87                     nificant power savings as everything in the system is put
88                     into a low-power  state,  except  for  memory,  which  is
89                     placed in self-refresh mode to retain its contents.
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91              disk   ACPI  state  S4 (Suspend-to-disk).  This state offers the
92                     greatest power savings, and  can  be  used  even  in  the
93                     absence  of  low-level platform support for power manage‐
94                     ment.  This state operates similarly  to  Suspend-to-RAM,
95                     but  includes  a final step of writing memory contents to
96                     disk.
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98              off    ACPI state  S5  (Poweroff).   This  is  done  by  calling
99                     '/sbin/shutdown'.   Not officially supported by ACPI, but
100                     it usually works.
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102              no     Don't suspend, only set the RTC wakeup time.
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104              on     Don't suspend, but read the RTC  device  until  an  alarm
105                     time appears.  This mode is useful for debugging.
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107              disable
108                     Disable a previously set alarm.
109
110              show   Print   alarm   information  in  format:  "alarm:  off|on
111                     <time>".  The time is in  ctime()  output  format,  e.g.,
112                     "alarm: on  Tue Nov 16 04:48:45 2010".
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114       -n, --dry-run
115              This  option  does everything apart from actually setting up the
116              alarm, suspending the system, or waiting for the alarm.
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118       -s, --seconds seconds
119              Set the wakeup time to seconds in the future from now.
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121       -t, --time time_t
122              Set the wakeup time to the absolute time time_t.  time_t is  the
123              time  in  seconds  since 1970-01-01, 00:00 UTC.  Use the date(1)
124              tool to convert between human-readable time and time_t.
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126       -u, --utc
127              Assume that the hardware clock is set  to  UTC  (Universal  Time
128              Coordinated), regardless of the contents of the adjtime file.
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130       -v, --verbose
131              Be verbose.
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133       -V, --version
134              Display version information and exit.
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136       -h, --help
137              Display help text and exit.
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NOTES

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

145       /etc/adjtime
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HISTORY

148       The  program  was  posted  several times on LKML and other lists before
149       appearing in kernel commit message for Linux  2.6  in  the  GIT  commit
150       87ac84f42a7a580d0dd72ae31d6a5eb4bfe04c6d.
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AUTHORS

153       The  program  was  written  by  David Brownell <dbrownell@users.source‐
154       forge.net> and improved by Bernhard Walle <bwalle@suse.de>.
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157       This is free software.  You may redistribute copies  of  it  under  the
158       terms       of       the      GNU      General      Public      License
159       <http://www.gnu.org/licenses/gpl.html>.  There is NO WARRANTY,  to  the
160       extent permitted by law.
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SEE ALSO

163       hwclock(8), date(1)
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AVAILABILITY

166       The  rtcwake command is part of the util-linux package and is available
167       from the Linux Kernel  Archive  ⟨https://www.kernel.org/pub/linux/utils
168       /util-linux/⟩.
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172util-linux                         June 2015                        RTCWAKE(8)
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