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XTEND(8)		FreeBSD System Manager's Manual 	      XTEND(8)

NAME
     xtend -- X-10 daemon

SYNOPSIS
     /usr/libexec/xtend

DESCRIPTION
     Xtend interfaces between user-level programs and the TW523 X-10 con-
     troller.  It logs all packets received from the TW523, attempts to track
     the status of all X-10 devices, and accepts socket connections from user-
     level client programs that need to manipulate X-10 devices.

     When xtend is started, it forks, releases the controlling terminal, then
     opens its log file, where it subsequently records all X-10 activity and
     diagnostic messages.  It then begins processing packets received from the
     TW523 and accepting connections one at a time from clients wishing to
     issue X-10 commands.  Xtend is started from /etc/rc.i386 startup script
     if enabled in /etc/rc.conf script.

     Sending xtend a SIGHUP causes it to close and reopen its log file.  This
     is useful in shell scripts that rotate the log files to keep them from
     growing indefinitely.  If xtend receives a SIGTERM, it shuts down grace-
     fully and exits.  A SIGPIPE causes xtend to abort the current client con-
     nection.

     Xtend communicates with client processes by a simple protocol in which a
     one-line command is sent by the client, and is acknowledged by a one-line
     response from the daemon.

     Xtend understands four types of commands:

     status H U   where H is a single letter house code, and U is a numeric
		  unit code, causes xtend to respond with one line of status
		  information about the specified device.

     send H U N   where H is a single-letter house code, U is either a numeric
		  unit code or a function code (see source file
		  xtend/packet.c) for a list, and N is a number indicating the
		  number of times (usually 2) the packet is to be transmitted
		  without gaps, causes xtend to perform the specified X-10
		  transmission.  If the transmission was apparently success-
		  ful, a single-line response containing OK is issued, other-
		  wise a single-line response containing ERROR is produced.

     dump	  causes xtend to dump the current status of all devices to an
		  ASCII file in the spool directory.  The response OK is
		  issued, regardless of whether the status dump was success-
		  ful.

     monitor H U  causes xtend to add the current client socket connection to
		  a list of clients that are to be notified about activity
		  concerning the specified X-10 device.  The single-line
		  acknowledgement OK is returned if the maximum (currently 5)
		  number of such clients was not exceeded, otherwise ERROR is
		  returned.  Xtend then returns to its normal mode of accept-
		  ing connections from clients.  However, each subsequent
		  change in the status of the specified device will cause
		  xtend to write one line of status information for the device
		  (in the same format as produced by the status command) to
		  the saved socket.  This feature is useful for writing pro-
		  grams that need to monitor the activity of devices, like
		  motion detectors, that can perform X-10 transmissions.

OPTIONS
     None.

SEE ALSO
     xten(1), tw(4)

FILES
     /dev/tw0			 the TW523 special file
     /var/run/tw523		 socket for client connections
     /var/run/xtend.pid 	 pid file
     /var/spool/xten/Log	 log file
     /var/spool/xten/Status	 device status file (binary)
     /var/spool/xten/status.out  ASCII dump of device status

BUGS
     There is currently no timeout on client socket connections, so a hung
     client program can prevent other clients from accessing the daemon.

     Xtend does the best it can at trying to track device status, but there is
     usually no way it can tell when a device has been operated manually.
     This is due to the fact that most X-10 devices are not able to respond to
     queries about their status.

AUTHORS
     Eugene W. Stark <stark@cs.sunysb.edu>

FreeBSD 4.9		       October 30, 1993 		   FreeBSD 4.9

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