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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | NOTES | FILES | HISTORY | AUTHORS | COPYRIGHT | SEE ALSO | AVAILABILITY | COLOPHON |
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RTCWAKE(8) System Administration RTCWAKE(8)
rtcwake - enter a system sleep state until specified wakeup time
rtcwake [options] [-d device] [-m standby_mode] {-s seconds|-t
time_t}
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 may 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.
rtcwake tries to avoid this problem and it waits to terminal to
settle down before entering a system sleep.
-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 timestamp 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.
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.
/etc/adjtime
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.
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.
hwclock(8), date(1)
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/⟩.
This page is part of the util-linux (a random collection of Linux
utilities) project. Information about the project can be found
at ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you
have a bug report for this manual page, send it to
util-linux@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
2020-12-18. (At that time, the date of the most recent commit
that was found in the repository was 2020-12-17.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
util-linux June 2015 RTCWAKE(8)
Pages that refer to this page: adjtime_config(5), hwclock(8)
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