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GPSFAKE(1)		      GPSD Documentation		    GPSFAKE(1)

       gpsfake - test harness for gpsd,	simulating a GPS

       gpsfake [-1] [-h] [-b] [-c interval] [-i] [-D debuglevel] [-l]
	       [-m monitor] [-g] [-G] [-n] [-o options]	[-p] [-P port] [-q]
	       [-r initcmd] [-s	speed] [-S] [-u] [-t] [-T] [-v]	[-W timeout]

       gpsfake is a test harness for gpsd and its clients. It opens a pty
       (pseudo-TTY), launches a	gpsd instance that thinks the slave side of
       the pty is its GPS device, and repeatedly feeds the contents of one or
       more test logfiles through the master side to the GPS. If there are
       multiple	logfiles, sentences from them are interleaved in the order the
       files are specified.

       gpsfake does not	require	root privileges, and can be run	concurrently
       with a production gpsd instance without causing problems.

       The logfiles may	contain	packets	in any supported format, including in
       particular NMEA,	SiRF, TSIP, or Zodiac. Leading lines beginning with #
       will be treated as comments and ignored,	except in the following
       special cases:

       o   a comment of	the form #Date:	yyyy-mm-dd (ISO8601 date format) may
	   be used to set the initial date for the log.

       o   a comment of	the form #Serial: [0-9]* [78][NOE][12] may be used to
	   set serial parameters for the log - baud rate, word length, stop

       o   a comment of	the form #Transport: UDP may be	used to	fake a UDP
	   source rather than the normal pty.

       The gpsd	instance is run	in foreground. The thread sending fake GPS
       data to the daemon is run in background.

       With the	-1 option, the logfile is interpreted once only	rather than
       repeatedly. This	option is intended to facilitate regression testing.

       The -b enables a	twirling-baton progress	indicator on standard error.
       At termination, it reports elapsed time.

       The -c sets the delay between sentences in seconds. Fractional values
       of seconds are legal. The default is zero (no delay).

       The -l makes the	program	dump a line or packet number just before each
       sentence	is fed to the daemon. If the sentence is textual (e.g. NMEA),
       the text	is dumped as well. If not, the packet will be dumped in
       hexadecimal (except for RTCM packets, which aren't dumped at all). This
       option is useful	for checking that gpsfake is getting packet boundaries

       The -i is for single-stepping through logfiles. It dumps	the line or
       packet number (and the sentence if the protocol is textual) followed by
       "? ". Only when the user	keys Enter is the line actually	fed to gpsd.

       The -m specifies	a monitor program inside which the daemon should be
       run. This option	is intended to be used with valgrind(1), gdb(1)	and
       similar programs.

       The -g and -G options use the monitor facility to run the gpsd instance
       within gpsfake under control of gdb or lldb, respectively. They also
       disable the timeout on daemon inactivity, to allow for breakpointing.
       If necessary, the timeout can be	reenabled by a subsequent -W.

       The -o specifies	options	to pass	to the daemon. The -n option passes -n
       to start	the daemon reading the GPS without waiting for a client
       (equivalent to -o "-n").	The -D passes a	-D option to the daemon: thus
       -D 4 is shorthand for -o	"-D 4".

       The -p ("pipe") option sets watcher mode	and dumps the NMEA and GPSD
       notifications generated by the log to standard output. This is useful
       for regression-testing.

       The -P ("port") option sets the daemon's	listening port.

       The -q tells gpsfake to suppress	normal progress	output and thus	act in
       a quiet manner.

       The -r specifies	an initialization command to use in pipe mode. The
       default is ?WATCH={"enable":true,"json":true}.

       The -s sets the baud rate for the slave tty. The	default	is 4800.

       The option -S tells gpsfake to insert realistic delays in the test
       input rather than trying	to stuff it through the	daemon as fast as
       possible. This will make	the test(s) run	much slower, but avoids	flaky
       failures	due to machine lode and	possible race conditions in the	pty

       The -t forces the test framework	to use TCP rather than pty devices.
       Besides being a test of TCP source handling, this may be	useful for
       testing from within chroot jails	where access to	pty devices is locked

       The -T makes gpsfake print some system information and then exits.

       The -u forces the test framework	to use UDP rather than pty devices.
       Besides being a test of UDP source handling, this may be	useful for
       testing from within chroot jails	where access to	pty devices is locked

       The -v enables verbose progress reports to stderr. It is	mainly useful
       for debugging gpsfake itself.

       The -W ("wait") option sets the timeout on daemon inactivity, in
       seconds.	The default timeout is 60 seconds, and a value of 0 suppresses
       the timeout altogether. Note that the actual timeout is longer due to
       internal	delays,	typically by about 20 seconds.

       The -x dumps packets as gpsfake gathers them. It	is mainly useful for
       debugging gpsfake itself.

       The -h makes gpsfake print a usage message and exit.

       The argument must be the	name of	a file containing the data to be
       cycled at the device.  gpsfake will print a notification	each time it

       Normally, gpsfake creates a pty for each	logfile	and passes the slave
       side of the device to the daemon. If the	header comment in the logfile
       contains	the string "UDP", packets are instead shipped via UDP port
       5000 to the address You	can monitor them with this:
       tcpdump -s0 -n -A -i lo udp and port 5000.

       Certain magic comments in test load headers can change the conditions
       of the test. These are:

	   May contain a serial-port setting such as 4800 7N2 -	baud rate
	   followed by 7 or 8 for byte length, N or O or E for parity and 1 or
	   2 for stop bits. The	test is	run with those settings	on the slave
	   port	that the daemon	sees.

	   Values 'TCP'	and 'UDP' force	the use	of TCP and UDP feeds
	   respectively	(the default is	a pty).

	   Must	be followed by two whitespace-separated	fields,	a delimiter
	   character and a numeric delay in seconds. Instead of	being broken
	   up by packet	boundaries, the	test load is split on the delimiters.
	   The delay is	performed after	each feed. Can be useful for imposing
	   write boundaries in the middle of packets.

       gpsfake is a trivial wrapper around a Python module, also named
       gpsfake,	that can be used to fully script sessions involving a gpsd
       instance, any number of client sessions,	and any	number of fake GPSes
       feeding the daemon instance with	data from specified sentence logs.

       Source and embedded documentation for this module is shipped with the
       gpsd development	tools. You can use it to torture-test either gpsd
       itself or any gpsd-aware	client application.

       Logfiles	for the	use with gpsfake can be	retrieved using	gpspipe,
       gpscat, or gpsmon from the gpsd distribution, or	any other application
       which is	able to	create a compatible output.

       If gpsfake exits	with "Cannot execute gpsd: executable not found." the
       environment variable GPSD_HOME can be set to the	path where gpsd	can be
       found. (instead of adding that folder to	the PATH environment variable

       gpsd(8),	gps(1),	libgps(3), libgpsmm(3),	gpsctl(1), gpspipe(1),
       gpsprof(1) gpsmon(1).

       Eric S. Raymond <>.

The GPSD Project		  12 Feb 2005			    GPSFAKE(1)


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