RTCWAKE(8) System Administration RTCWAKE(8)
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 the 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