# man > rtcwake(8) [RTCWAKE(8)](https://www.chedong.com/phpMan.php/man/RTCWAKE/8/markdown) System Administration [RTCWAKE(8)](https://www.chedong.com/phpMan.php/man/RTCWAKE/8/markdown) ## 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 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)](https://www.chedong.com/phpMan.php/man/hwclock/8/markdown) 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 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 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