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APMD(8) NetBSD System Manager's Manual APMD(8)
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apmd -- Advanced Power Management monitor daemon
apmd [-adlqsv] [-t rate] [-S sockname] [-m sockmode]
[-o sockowner:sockgroup] [-f devname]
The apmd daemon monitors the Advanced Power Management (APM) pseudo-
device, acting on signaled events and upon user requests as sent by the
apm(8) utility. The apmd daemon is only installed on supported plat-
The apmd is largely deprecated. Modern systems supporting ACPI should
rely on acpi(4), powerd(8), and the envsys(4) framework instead.
For suspend and standby request events delivered by the BIOS, or via
apm(8), apmd runs the appropriate configuration program (if one exists),
syncs the buffer cache to disk and initiates the requested mode. When
resuming after suspend or standby, apmd runs the appropriate configura-
tion utility (if one exists). For power status change events, apmd
fetches the current status and reports it via syslog(3) with logging
apmd announces the transition to standby mode with a single high tone on
the speaker (using the /dev/speaker device). Suspends are announced with
two high tones.
apmd periodically polls the APM driver for the current power state. If
the battery charge level changes substantially or the external power sta-
tus changes, the new status is logged. The polling rate defaults to once
per 10 minutes, but this may be altered by using the -t command-line
apmd supports the following options:
-a Any BIOS-initiated suspend or standby requests are ignored if
the system is connected to line current and not running from
batteries (user requests are still honored).
-d Enter debug mode, log to facility LOG_LOCAL1 and stay in the
foreground on the controlling terminal.
-f devname Specify an alternate device file name.
-l A low-battery event causes a suspend request to occur.
Use sockmode instead of `0660' for the mode of
Use sockowner:sockgroup instead of ``0:0'' for the
owner/group of /var/run/apmdev.
-q Do not announce suspend and standby requests on the speaker.
-s The current battery statistics are reported via syslog(3) and
exit without monitoring the APM status.
Specify an alternate socket name (used by apm(8) to communi-
cate with apmd).
-t rate Change the polling rate from 600 seconds to rate seconds.
-v Periodically log the power status via syslog(3).
When a client requests a suspend or stand-by mode, apmd does not wait for
positive confirmation that the requested mode has been entered before
replying to the client; to do so would mean the client does not get a
reply until the system resumes from its sleep state. Rather, apmd
replies with the intended state to the client and then places the system
in the requested mode after running the configuration script and flushing
the buffer cache.
Actions can be configured for the five transitions: suspend, standby,
resume, line or battery. The suspend and standby actions are run prior
to apmd performing any other actions (such as disk syncs) and entering
the new mode. The resume program is run after resuming from a stand-by
or suspended state.
The line and battery actions are run after switching power sources to AC
(line) or battery, respectively. The appropriate line or battery action
is also run upon the startup of apmd based on the current power source.
/etc/apm/battery Contain the host's customized actions. Each file must
be an executable binary or shell script suitable for
execution by the execve(2) function. If you wish to
have the same program or script control all transi-
tions, it may determine which transition is in progress
by examining its argv which is set to one of
suspend, standby, resume, line or battery. See
/usr/share/examples/apm/script for such an example
/var/run/apmdev The default UNIX-domain socket used for communication
with apm(8). The socket is protected by default to
mode 0660, UID 0, GID 0.
/dev/apmctl The default device used to control the APM kernel
execve(2), syslog(3), apm(4), speaker(4), apm(8), syslogd(8)
The apmd daemon appeared in NetBSD 1.3.
NetBSD 6.0 March 20, 2010 NetBSD 6.0