rtcwake(8) - Linux man page
Name
rtcwake - enter a system sleep state until specified wakeup timeSynopsis
rtcwake [-hvVlua] [-d device] [-m standby_mode] {-t time_t|-s seconds}Description
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.
Options
- -v | --verbose
- Be verbose.
- -h | --help
- Display a short help message that shows how to use the program.
- -V | --version
- Displays version information and exists.
- -a | --auto
- Reads the clock mode (whether the hardware clock is set to UTC or local time) from /etc/adjtime. That's the location where the hwclock(8) stores that information.
- -l | --local
- Assumes that the hardware clock is set to local time, regardless of the contents of /etc/adjtime.
- -u | --utc
- Assumes that the hardware clock is set to UTC (Universal Time Coordinated), regardless of the contents of /etc/adjtime.
- -d device | --device device
- Uses 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.
- -s seconds | --seconds seconds
- Sets the wakeup time to seconds in future from now.
- -t time_t | --time time_t
- Sets 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.
- -m mode | --mode mode
- Use standby state mode. Valid values 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.
- 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 usually working.
- no
- Don't suspend. The rtcwake command sets RTC wakeup time only.
- on
- Don't suspend, but read RTC device until alarm time appears. This mode is useful for debugging.
