1RTCWAKE(8) System Administration RTCWAKE(8)
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6 rtcwake - enter a system sleep state until specified wakeup time
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9 rtcwake [options] [-d device] [-m standby_mode] {-s seconds|-t time_t}
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12 This program is used to enter a system sleep state and to automatically
13 wake from it at a specified time.
14 This uses cross-platform Linux interfaces to enter a system sleep
16 state, and leave it no later than a specified time. It uses any RTC
17 framework driver that supports standard driver model wakeup flags.
18 This is normally used like the old apmsleep utility, to wake from a
20 suspend state like ACPI S1 (standby) or S3 (suspend-to-RAM). Most
21 platforms can implement those without analogues of BIOS, APM, or ACPI.
22 On some systems, this can also be used like nvram-wakeup, waking from
24 states like ACPI S4 (suspend to disk). Not all systems have persistent
25 media that are appropriate for such suspend modes.
26 Note that alarm functionality depends on hardware; not every RTC is
28 able to setup an alarm up to 24 hours in the future.
29 The suspend setup maybe be interrupted by active hardware; for example
31 wireless USB input devices that continue to send events for some frac‐
32 tion of a second after the return key is pressed. rtcwake tries to
33 avoid this problem and it waits to terminal to settle down before
34 entering a system sleep.
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38 -A, --adjfile file
39 Specify an alternative path to the adjust file.
40 -a, --auto
42 Read the clock mode (whether the hardware clock is set to UTC or
43 local time) from the adjtime file, where hwclock(8) stores that
44 information. This is the default.
45 --date timestamp
47 Set the wakeup time to the value of the timestamp. Format of
48 the timestamp can be any of the following:
49 YYYYMMDDhhmmss
51 YYYY-MM-DD hh:mm:ss
52 YYYY-MM-DD hh:mm (seconds will be set to 00)
53 YYYY-MM-DD (time will be set to 00:00:00)
54 hh:mm:ss (date will be set to today)
55 hh:mm (date will be set to today, seconds to 00)
56 tomorrow (time is set to 00:00:00)
57 +5min
58 -d, --device device
60 Use the specified device instead of rtc0 as realtime clock.
61 This option is only relevant if your system has more than one
62 RTC. You may specify rtc1, rtc2, ... here.
63 -l, --local
65 Assume that the hardware clock is set to local time, regardless
66 of the contents of the adjtime file.
67 --list-modes
69 List available --mode option arguments.
70 -m, --mode mode
72 Go into the given standby state. Valid values for mode are:
73 standby
75 ACPI state S1. This state offers minimal, though real,
76 power savings, while providing a very low-latency transi‐
77 tion back to a working system. This is the default mode.
78 freeze The processes are frozen, all the devices are suspended
80 and all the processors idled. This state is a general
81 state that does not need any platform-specific support,
82 but it saves less power than Suspend-to-RAM, because the
83 system is still in a running state. (Available since
84 Linux 3.9.)
85 mem ACPI state S3 (Suspend-to-RAM). This state offers sig‐
87 nificant power savings as everything in the system is put
88 into a low-power state, except for memory, which is
89 placed in self-refresh mode to retain its contents.
90 disk ACPI state S4 (Suspend-to-disk). This state offers the
92 greatest power savings, and can be used even in the
93 absence of low-level platform support for power manage‐
94 ment. This state operates similarly to Suspend-to-RAM,
95 but includes a final step of writing memory contents to
96 disk.
97 off ACPI state S5 (Poweroff). This is done by calling
99 '/sbin/shutdown'. Not officially supported by ACPI, but
100 it usually works.
101 no Don't suspend, only set the RTC wakeup time.
103 on Don't suspend, but read the RTC device until an alarm
105 time appears. This mode is useful for debugging.
106 disable
108 Disable a previously set alarm.
109 show Print alarm information in format: "alarm: off|on
111 <time>". The time is in ctime() output format, e.g.
112 "alarm: on Tue Nov 16 04:48:45 2010".
113 -n, --dry-run
115 This option does everything apart from actually setting up the
116 alarm, suspending the system, or waiting for the alarm.
117 -s, --seconds seconds
119 Set the wakeup time to seconds in the future from now.
120 -t, --time time_t
122 Set the wakeup time to the absolute time time_t. time_t is the
123 time in seconds since 1970-01-01, 00:00 UTC. Use the date(1)
124 tool to convert between human-readable time and time_t.
125 -u, --utc
127 Assume that the hardware clock is set to UTC (Universal Time
128 Coordinated), regardless of the contents of the adjtime file.
129 -v, --verbose
131 Be verbose.
132 -V, --version
134 Display version information and exit.
135 -h, --help
137 Display help text and exit.
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140 Some PC systems can't currently exit sleep states such as mem using
141 only the kernel code accessed by this driver. They need help from
142 userspace code to make the framebuffer work again.
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145 /etc/adjtime
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148 The program was posted several times on LKML and other lists before
149 appearing in kernel commit message for Linux 2.6 in the GIT commit
150 87ac84f42a7a580d0dd72ae31d6a5eb4bfe04c6d.
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153 The program was written by David Brownell <dbrownell@users.source‐
154 forge.net> and improved by Bernhard Walle <bwalle@suse.de>.
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157 This is free software. You may redistribute copies of it under the
158 terms of the GNU General Public License
159 <http://www.gnu.org/licenses/gpl.html>. There is NO WARRANTY, to the
160 extent permitted by law.
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163 hwclock(8), date(1)
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166 The rtcwake command is part of the util-linux package and is available
167 from the Linux Kernel Archive ⟨https://www.kernel.org/pub/linux/utils
168 /util-linux/⟩.
169util-linux June 2015 RTCWAKE(8)