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 may be interrupted by active hardware; for example
31 wireless USB input devices that continue to send events for some
32 fraction of a second after the return key is pressed. rtcwake tries to
33 avoid this problem and it waits to the terminal to settle down before
34 entering a system sleep.
35
37 -A, --adjfile file
38 Specify an alternative path to the adjust file.
39 -a, --auto
41 Read the clock mode (whether the hardware clock is set to UTC or
42 local time) from the adjtime file, where hwclock(8) stores that
43 information. This is the default.
44 --date timestamp
46 Set the wakeup time to the value of the timestamp. Format of the
47 timestamp can be any of the following:
48 ┌────────────────────┬───────────────────────────┐
50 │ │ │
51 │YYYYMMDDhhmmss │ │
52 ├────────────────────┼───────────────────────────┤
53 │ │ │
54 │YYYY-MM-DD hh:mm:ss │ │
55 ├────────────────────┼───────────────────────────┤
56 │ │ │
57 │YYYY-MM-DD hh:mm │ (seconds will be set to │
58 │ │ 00) │
59 ├────────────────────┼───────────────────────────┤
60 │ │ │
61 │YYYY-MM-DD │ (time will be set to │
62 │ │ 00:00:00) │
63 ├────────────────────┼───────────────────────────┤
64 │ │ │
65 │hh:mm:ss │ (date will be set to │
66 │ │ today) │
67 ├────────────────────┼───────────────────────────┤
68 │ │ │
69 │hh:mm │ (date will be set to │
70 │ │ today, seconds to 00) │
71 ├────────────────────┼───────────────────────────┤
72 │ │ │
73 │tomorrow │ (time is set to 00:00:00) │
74 ├────────────────────┼───────────────────────────┤
75 │ │ │
76 │+5min │ │
77 └────────────────────┴───────────────────────────┘
78 -d, --device device
80 Use the specified device instead of rtc0 as realtime clock. This
81 option is only relevant if your system has more than one RTC. You
82 may specify rtc1, rtc2, ... here.
83 -l, --local
85 Assume that the hardware clock is set to local time, regardless of
86 the contents of the adjtime file.
87 --list-modes
89 List available --mode option arguments.
90 -m, --mode mode
92 Go into the given standby state. Valid values for mode are:
93 standby
95 ACPI state S1. This state offers minimal, though real, power
96 savings, while providing a very low-latency transition back to
97 a working system. This is the default mode.
98 freeze
100 The processes are frozen, all the devices are suspended and all
101 the processors idled. This state is a general state that does
102 not need any platform-specific support, but it saves less power
103 than Suspend-to-RAM, because the system is still in a running
104 state. (Available since Linux 3.9.)
105 mem
107 ACPI state S3 (Suspend-to-RAM). This state offers significant
108 power savings as everything in the system is put into a
109 low-power state, except for memory, which is placed in
110 self-refresh mode to retain its contents.
111 disk
113 ACPI state S4 (Suspend-to-disk). This state offers the greatest
114 power savings, and can be used even in the absence of low-level
115 platform support for power management. This state operates
116 similarly to Suspend-to-RAM, but includes a final step of
117 writing memory contents to disk.
118 off
120 ACPI state S5 (Poweroff). This is done by calling
121 '/sbin/shutdown'. Not officially supported by ACPI, but it
122 usually works.
123 no
125 Don’t suspend, only set the RTC wakeup time.
126 on
128 Don’t suspend, but read the RTC device until an alarm time
129 appears. This mode is useful for debugging.
130 disable
132 Disable a previously set alarm.
133 show
135 Print alarm information in format: "alarm: off|on <time>". The
136 time is in ctime() output format, e.g., "alarm: on Tue Nov 16
137 04:48:45 2010".
138 -n, --dry-run
140 This option does everything apart from actually setting up the
141 alarm, suspending the system, or waiting for the alarm.
142 -s, --seconds seconds
144 Set the wakeup time to seconds in the future from now.
145 -t, --time time_t
147 Set the wakeup time to the absolute time time_t. time_t is the time
148 in seconds since 1970-01-01, 00:00 UTC. Use the date(1) tool to
149 convert between human-readable time and time_t.
150 -u, --utc
152 Assume that the hardware clock is set to UTC (Universal Time
153 Coordinated), regardless of the contents of the adjtime file.
154 -v, --verbose
156 Be verbose.
157 -h, --help
159 Display help text and exit.
160 -V, --version
162 Print version and exit.
163
165 Some PC systems can’t currently exit sleep states such as mem using
166 only the kernel code accessed by this driver. They need help from
167 userspace code to make the framebuffer work again.
168
170 /etc/adjtime
171
173 The program was posted several times on LKML and other lists before
174 appearing in kernel commit message for Linux 2.6 in the GIT commit
175 87ac84f42a7a580d0dd72ae31d6a5eb4bfe04c6d.
176
178 The program was written by David Brownell
179 <dbrownell@users.sourceforge.net> and improved by Bernhard Walle
180 <bwalle@suse.de>.
181
183 This is free software. You may redistribute copies of it under the
184 terms of the GNU General Public License
185 <http://www.gnu.org/licenses/gpl.html>. There is NO WARRANTY, to the
186 extent permitted by law.
187
189 adjtime_config(5), hwclock(8), date(1)
190
192 For bug reports, use the issue tracker at
193 https://github.com/util-linux/util-linux/issues.
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196 The rtcwake command is part of the util-linux package which can be
197 downloaded from Linux Kernel Archive
198 <https://www.kernel.org/pub/linux/utils/util-linux/>.
199util-linux 2.38.1 2022-05-11 RTCWAKE(8)