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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	 oper‐
       ating 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 opera‐
       tion.

       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 lap‐
	      tops 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.	Hiber‐
	      nation 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 manage‐
	      ment.

       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 immedi‐
	      ately 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 man‐
	      agement 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.	  Bat‐
       tery 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  sub‐
	      system.	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 unimpor‐
	      tance.  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  mak‐
	      ing 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  specifi‐
       cation  version	1.2;  however it fails to support some of the advanced
       features of APM 1.2, such as reporting the conditions of multiple  bat‐
       teries.	(Multiple batteries are currently treated as if they were just
       one large one.)

       Estimates of charge and discharge rates and times can be	 very  inaccu‐
       rate.

       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 main‐
       tainer is Avery Pennarun (apenwarr@worldvisions.ca).

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

				 January 2004			       APMD(8)
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