158 lines
5.8 KiB
Groff
158 lines
5.8 KiB
Groff
.\" Copyright (c) 2007, SUSE LINUX Products GmbH
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.\" Bernhard Walle <bwalle@suse.de>
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.\"
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.\" This program is free software; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License
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.\" as published by the Free Software Foundation; either version 2
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.\" of the License, or (at your option) any later version.
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.\"
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.\" This program is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public License
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.\" along with this program; if not, write to the Free Software
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.\" Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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.\" 02110-1301, USA.
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.\"
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.TH RTCWAKE 8 "July 2007" "util-linux" "System Administration"
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.SH NAME
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rtcwake - enter a system sleep state until specified wakeup time
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.SH SYNOPSIS
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.B rtcwake
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.RB [ options ]
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.RB [ \-d
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.IR device ]
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.RB [ \-m
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.IR standby_mode ]
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.RB { "\-t \fItime_t\fP" | "\-s \fIseconds\fP" }
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.SH DESCRIPTION
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This program is used to enter a system sleep state until specified wakeup time.
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.PP
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This uses cross-platform Linux interfaces to enter a system sleep state, and
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leave it no later than a specified time. It uses any RTC framework driver that
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supports standard driver model wakeup flags.
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.PP
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This is normally used like the old \fBapmsleep\fP utility, to wake from a suspend
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state like ACPI S1 (standby) or S3 (suspend-to-RAM). Most platforms can
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implement those without analogues of BIOS, APM, or ACPI.
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.P
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On some systems, this can also be used like \fBnvram-wakeup\fP, waking from states
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like ACPI S4 (suspend to disk). Not all systems have persistent media that are
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appropriate for such suspend modes.
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.SS Options
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.TP
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\fB-v\fP | \fB--verbose\fP
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Be verbose.
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.TP
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\fB-h\fP | \fB--help\fP
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Display help text and exit.
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.TP
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\fB-V\fP | \fB--version\fP
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Display version information and exit.
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.TP
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\fB-n\fP | \fB--dry-run\fP
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This option does everything apart from actually setting up the alarm,
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suspending the system, or waiting for the alarm.
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.TP
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\fB-A\fP | \fB--adjfile\fP \fIfile\fP
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Specifies an alternative path to the adjust file.
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.TP
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\fB-a\fP | \fB--auto\fP
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Reads the clock mode (whether the hardware clock is set to UTC or local time)
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from \fIadjtime\fP file. That's the location where the
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.BR hwclock (8)
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stores that information. This is the default.
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.TP
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\fB-l\fP | \fB--local\fP
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Assumes that the hardware clock is set to local time, regardless of the
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contents of \fIadjtime\fP file.
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.TP
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\fB-u\fP | \fB--utc\fP
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Assumes that the hardware clock is set to UTC (Universal Time Coordinated),
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regardless of the contents of \fIadjtime\fP file.
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.TP
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\fB-d\fP \fIdevice\fP | \fB--device\fP \fIdevice\fP
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Uses \fIdevice\fP instead of \fIrtc0\fP as realtime clock. This option
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is only relevant if your system has more than one RTC. You may specify
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\fIrtc1\fP, \fIrtc2\fP, ... here.
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.TP
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\fB-s\fP \fIseconds\fP | \fB--seconds\fP \fIseconds\fP
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Sets the wakeup time to \fIseconds\fP in future from now.
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.TP
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\fB-t\fP \fItime_t\fP | \fB--time\fP \fItime_t\fP
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Sets the wakeup time to the absolute time \fItime_t\fP. \fItime_t\fP
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is the time in seconds since 1970-01-01, 00:00 UTC. Use the
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.BR date (1)
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tool to convert between human-readable time and \fItime_t\fP.
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.TP
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\fB-m\fP \fImode\fP | \fB--mode\fP \fImode\fP
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Use standby state \fImode\fP. Valid values are:
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.RS
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.TP
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.B standby
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ACPI state S1. This state offers minimal, though real, power savings, while
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providing a very low-latency transition back to a working system. This is the
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default mode.
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.TP
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.B mem
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ACPI state S3 (Suspend-to-RAM). This state offers significant power savings as
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everything in the system is put into a low-power state, except for memory,
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which is placed in self-refresh mode to retain its contents.
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.TP
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.B freeze
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The processes are frozen, all the devices are suspended and all the processors
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idles. This state is a general state that does not need any platform specific
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support, but it saves less power than susepnd to RAM, because the system is
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still in a running state. (since Linux 3.9)
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.TP
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.B disk
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ACPI state S4 (Suspend-to-disk). This state offers the greatest power savings,
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and can be used even in the absence of low-level platform support for power
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management. This state operates similarly to Suspend-to-RAM, but includes a
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final step of writing memory contents to disk.
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.TP
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.B off
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ACPI state S5 (Poweroff). This is done by calling '/sbin/shutdown'.
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Not officially supported by ACPI, but usually working.
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.TP
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.B no
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Don't suspend. The rtcwake command sets RTC wakeup time only.
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.TP
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.B on
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Don't suspend, but read RTC device until alarm time appears. This mode is
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useful for debugging.
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.TP
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.B disable
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Disable previously set alarm.
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.TP
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.B show
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Print alarm information in format: "alarm: off|on <time>".
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The time is in ctime() output format, e.g. "alarm: on Tue Nov 16 04:48:45 2010".
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.RE
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.PP
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.SH FILES
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.I @ADJTIME_PATH@
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.SH NOTES
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Some PC systems can't currently exit sleep states such as \fImem\fP
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using only the kernel code accessed by this driver.
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They need help from userspace code to make the framebuffer work again.
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.SH HISTORY
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The program was posted several times on LKML and other lists
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before appearing in kernel commit message for Linux 2.6 in the GIT
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commit 87ac84f42a7a580d0dd72ae31d6a5eb4bfe04c6d.
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.SH AVAILABILITY
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The rtcwake command is part of the util-linux package and is available from
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ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
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.SH AUTHOR
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The program was written by David Brownell <dbrownell@users.sourceforge.net>
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and improved by Bernhard Walle <bwalle@suse.de>.
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.SH COPYRIGHT
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This is free software. You may redistribute copies of it under the terms
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of the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.
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There is NO WARRANTY, to the extent permitted by law.
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.SH "SEE ALSO"
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.BR hwclock (8),
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.BR date (1)
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