Manual Pages  — APMD

The apmd utility uses the device /dev/apmctl to issue ioctl(2) requests for monitoring events and for controlling the APM system. This device file is opened exclusively, so only a single apmd process can be running at any time.

When apmd receives an APM event, it forks a child process to execute the commands specified in the configuration file and then continues listening for more events. The child process executes the commands specified, one at a time and in the order that they are listed.

While apmd is processing the command list for SUSPEND/STANDBY requests, the APM kernel device driver issues notifications to APM BIOS once per second so that the BIOS knows that there are still some commands pending, and that it should not complete the request just yet.

The apmd utility creates the file /var/run/apmd.pid, and stores its process id there. This can be used to kill or reconfigure apmd.

apm_event SUSPENDREQ {
       exec "sync && sync && sync";
       exec "sleep 1";
       exec "zzz";
}

• The apm_event keyword ‘apm_event’ is the keyword which indicates the start of configuration for each event.
• APM events If you wish to execute the same commands for different events, the event names should be delimited by a comma. The following are valid event names:

  	- Events ignored by the kernel if apmd is running:

  STANDBYREQ USERSTANDBYREQ SUSPENDREQ
  	should include sync in the command list,
  USERSUSPENDREQ
  	should include sync in the command list,
  BATTERYLOW	only zzz should be specified in the command list.

  	- Events passed to apmd after kernel handling:
  NORMRESUME CRITRESUME STANDBYRESUME POWERSTATECHANGE UPDATETIME CAPABILITIESCHANGE

  Other events will not be sent to apmd.

• command line syntax In the example above, the three lines beginning with ‘exec’ are commands for the event. Each line should be terminated with a semicolon. The command list for the event should be enclosed by ‘{’ and ‘}’. The apmd utility uses /bin/sh for double-quotation enclosed command execution, just as with system(3). Each command is executed in order until the end of the list is reached or a command finishes with a non-zero status code. The apmd utility will report any failed command's status code via syslog(3) and will then reject the request event posted by the APM BIOS.
• Built-in functions You can also specify apmd built-in functions instead of command lines. A built-in function name should be terminated with a semicolon, just as with a command line. The following built-in functions are currently supported:

  - reject
  	Reject last request posted by APM BIOS. This can be used to reject a SUSPEND request when the LCD is closed and put the system in a STANDBY state instead.