Provided by: util-linux_2.37.2-4ubuntu3.4_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.

       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.

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 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.

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>.

COPYRIGHT

       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)

REPORTING BUGS

       For bug reports, use the issue tracker at https://github.com/karelzak/util-linux/issues.

AVAILABILITY

       The rtcwake command is part of the util-linux package which can be downloaded from Linux
       Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.