apmd

APMD(8)                                                                APMD(8)



NAME
       apmd - Advanced Power Management (APM) daemon

SYNOPSIS
       apmd [ -TVWciqv ] [ -P program ] [ -T seconds ] [ -c seconds ] [ -p
       percent ] [ -v level ] [ -w percent ]

DESCRIPTION
       apmd is an monitoring daemon for the Advanced Power Management (APM)
       subsystem.  The APM subsystem consists of power-management hardware,
       firmware usually referred to as the APM BIOS and a driver in the
       operating system kernel.  The daemon can execute a program (usually a
       shell script) when events are reported by the APM subsystem, and will
       log, via syslogd(8), certain changes in power status.  When the
       available battery power becomes very low it can alert the user.

       When the APM subsystem notifies the daemon of a pending suspend or
       standby request, apmd will run a proxy program, log the event, sync(2)
       data to the disk and then tell the APM subsystem to continue its
       operation.

       Preparations for power management events are made mainly by the proxy
       program specified using the -P option.  The proxy program is invoked
       with one or two arguments:

       start  Invoked when the daemon starts.

       stop   Invoked when the daemon stops.

       standby ( system | user )
              Invoked when the APM subsystem reports that standby has been
              initiated.  The second parameter indicates whether firmware
              ("system") or software ("user") was the originator of the event.

              The "standby" mode conserves power but leaves the machine able
              to respond almost immediately to user activity.  Most laptops
              can't stay in standby mode on battery power for more than a few
              hours or a day.  Normally, nothing special needs to be done to
              prepare for "standing by".

       suspend ( system | user )
              Invoked when the APM subsystem reports that suspension has been
              initiated.  The second parameter indicates whether firmware
              ("system") or software ("user") was the originator of the event.

              The "suspend" mode aggressively conserves power.  Usually this
              involves shutting off power to all devices except the CPU core
              and memory, which are put into a very low power mode.  Most
              laptops can stay suspended, using battery power alone, for
              several days.  ("Hibernation" is a kind of super-suspend, where
              all that state is written to disk and the machine uses no power.
              Hibernation is treated like suspension by the APM subsystem.)

              Before suspending, PCMCIA devices may need to be disabled using
              cardctl(8), and some modular device drivers may need to be
              unloaded if they have not been designed to support power
              management.

       resume ( suspend | standby | critical )
              Invoked when the APM subsystem reports that computer has resumed
              normal operation.  The second parameter indicates the kind of
              event from which the system is resuming.  (A "critical" suspend
              is a suspension that the APM subsystem performs in an emergency.
              Some kernels do not pass this event to user space.  If apmd
              receives the event, it acknowledges the event and exits
              immediately without logging or running the proxy program.)

              When resuming, PCMCIA devices may need to be re-enabled using
              cardctl(8), and some modular drivers may need to be reloaded.
              Note that in the case of a critical suspend, the system state
              may not have been completely saved.

       change power
              Invoked when the APM subsystem reports a change in power status,
              such as a switch from mains to battery power.

       change battery
              Invoked when the APM subsystem reports that the charge of one or
              more batteries is low.  A few minutes of battery power may
              remain.

       change capability
              Invoked when the APM subsystem reports some change in power
              management capabilities.  It may have been caused by operation
              of a setup utility, or by the installation or removal of
              devices.

       apmd emits various messages, most of which are self-explanatory.
       Battery status log entries contain three fields, separated by commas.
       The first field indicates how full the battery is as a percentage of
       its capacity.  The second field indicates whether the battery is
       charging, not charging, or discharging.  When possible, apmd adds in
       parentheses its estimate of the rate of charging or discharging.  The
       third field indicates how much time the battery can or could be used to
       power the computer.  This information is provided by the APM subsystem.
       When possible, apmd adds in parentheses its own estimate of the battery
       life (if discharging) or of the time required to charge the battery
       fully (if charging).

OPTIONS
       -P program, --proxy program
              Specifies the proxy program to execute when events are received.
              See above for information about the arguments supplied to this
              program.

       -T [seconds] , --proxy-timeout [seconds]
              Sets a time-out for the proxy.  Without this option (or with
              this option and a negative argument) apmd waits indefinitely for
              the proxy to finish.  If the proxy enters an infinite loop or
              wait then the machine may appear to have crashed.  If this
              option is given a positive integer argument then apmd will wait
              only that many seconds for the proxy to finish, after which it
              will log a warning, kill the proxy, and continue processing the
              event.  The default is 30 seconds.

       -V, --version
              Prints the version of the apmd program.

       -W, --wall
              In addition to logging low battery status (as determined either
              by the -w level or by the firmware) using syslog(2), apmd will,
              given this option, also use wall(1) to alert all users.  This is
              most useful if syslogd(8) is not set up to write ALERT messages
              to all users.  If both methods are used, more warnings will be
              made during the critical time period.

       -c [seconds] , --check [seconds]
              Controls how many seconds to wait for an event.  Without this
              option (or with this option and a negative argument) apmd waits
              indefinitely for an event.  If this option is given a positive
              integer argument then apmd will wait only that many seconds
              before checking the battery level and possibly sending out a
              warning, calling the proxy or making an entry in the log.  The
              default is 30 seconds.

       -i, --ignore-bios-battery-low
              Causes apmd to ignore a LOW BATTERY signal sent by the APM
              subsystem.  Some firmware signals a low battery at the wrong
              time.  Note that LOW BATTERY events may still be generated by
              apmd itself based on the warning level.

       -p percent, --percentage percent
              Controls how often the battery status is logged.  A new line is
              printed each time the battery content changes by percent_change
              if logging is enabled.  The default is 5.  Use a value greater
              than 100 to disable periodic logging of the battery level.

       -q, --quiet-bios-battery-low
              Causes apmd not to generate a warning when a LOW BATTERY signal
              is received from the APM subsystem.  The firmware on some
              machines produces an audible warning when power is about to be
              used up, so an extra warning may not be needed.

       -v [level] , --verbose [level]
              The daemon can generate messages of varying degrees of
              unimportance.  Each message is assigned one of the priority
              levels defined for the syslogd(8) subsystem, ranging from 0
              (EMERG, least unimportant) to 7 (DEBUG, most unimportant).  This
              option sets the threshold level above which messages are
              suppressed.  Without an argument it increments the threshold by
              1, thus making apmd more verbose.  The default is 5 (NOTICE).

       -w percent, --warn percent
              When the battery is not being charged and the battery content
              falls below the specified percent of capacity, and no such event
              has yet occurred in the current discharge cycle, apmd will log a
              warning at the ALERT log level to syslog(2) and generate a LOW
              BATTERY event.  If the -W or --wall option was given, the daemon
              will also use wall(1) to alert all users of impending doom.  The
              default warning level is 10.  Use a negative value to disable
              this feature.

       -h, --help
              Causes apmd to print a brief command summary and exit.


BUGS
       This daemon supports all APM events described in the APM BIOS
       specification version 1.2; however it fails to support some of the
       advanced features of APM 1.2, such as reporting the conditions of
       multiple batteries.  (Multiple batteries are currently treated as if
       they were just one large one.)

       Estimates of charge and discharge rates and times can be very
       inaccurate.

       There is no interaction yet with ACPI support as found in newer PC
       hardware.

FILES
       /dev/apm_bios
              Device through which apmd communicates with the Linux APM
              driver.

       /proc/apm
              APM driver status information

       /etc/apmd_proxy
              Proxy program that is run if none is specified.

       /etc/apm/apmd_proxy
              Proxy program that is run if none is specified. (Debian)

AUTHOR
       This program was written by Rik Faith (faith@cs.unc.edu) and may be
       freely distributed under the terms of the GNU General Public License.
       There is ABSOLUTELY NO WARRANTY for this program.  The current
       maintainer is Avery Pennarun (apenwarr@worldvisions.ca).

SEE ALSO
       apm(1), xapm(1), cardctl(8), syslogd(8).



                                 January 2004                          APMD(8)