Advanced Power Management
apmd monitors the advanced power
management device, apm(4), acting on signaled events and upon user requests as
sent by the apm(8) program.
For suspend and standby request events delivered by the BIOS, or
apmd runs the appropriate
configuration program (if one exists), syncs the buffer cache to disk and
initiates the requested state. When resuming after suspend or standby,
apmd runs the appropriate configuration program (if
When the power status changes (battery is connected or
apmd fetches the current status and
reports it via
syslog(3) with logging facility
The options are as follows:
apmdin automatic performance adjustment mode.
- 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).
apmdenters debug mode, logging to facility
LOG_LOCAL1, and stays in the foreground on the controlling terminal.
- Specify an alternate device file name, devname.
apmdin manual performance adjustment mode, initialising hw.setperf to 100.
apmdin manual performance adjustment mode, initialising hw.setperf to 0.
- Specify an alternate socket name, sockname. The socket is protected to mode 0660, UID 0, GID 0; this protects access to suspend requests to authorized users only.
- Current battery statistics are reported via
apmdexits without monitoring the APM status.
apmdperiodically polls the APM driver for the current power state. If the battery charge level changes substantially or the external power status changes, the new status is logged. The polling rate defaults to once per 10 minutes, but may be specified using the
When a client requests a suspend or stand-by state,
apmd does not wait for positive confirmation that
the requested state 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 state after
running the configuration script and flushing the buffer cache.
Actions can be configured for the following transitions: suspend,
hibernate, standby, resume, powerup, and powerdown. The suspend, hibernate
and standby actions are run prior to
any other actions (such as disk syncs) and entering the new state. The
resume program is run after resuming from a stand-by or suspended state. The
powerup and powerdown programs are run after the power status (AC connected
or not) changes, as well as after a resume (if the power status changed in
the mean time).
- Default device used to control the APM kernel driver.
- These files contain the host's customized actions. Each file must be an executable binary or shell script. A single program or script can be used to control all transitions by examining the name by which it was called, which is one of suspend, hibernate, standby, resume, powerup, or powerdown.
- Default UNIX-domain socket used for communication with apm(8).
syslog(3), apm(4), apm(8), sysctl(8)
Advanced Power Management (APM) BIOS Interface Specification (revision 1.2), Intel Corporation and Microsoft Corporation.
apmd command first appeared in
NetBSD 1.3. OpenBSD support
was added in OpenBSD 1.2.