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       gpsfake - test harness for gpsd, simulating a GPS


       gpsfake [-1] [-h] [-b] [-c interval] [-i] [-D debuglevel] [-l]
               [-m monitor] [-n] [-o options] [-p] [-r initcmd] [-s speed]
               [-v] [logfile...]


       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
       fuiles are specified.

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

       The logfiles may be of NMEA, SiRF packets, TSIP packets, or Zodiac
       packets. Leading lines beginning with # will be treated as comments and

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

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

       The -l option 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 right.

       The -i option 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 option 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 option uses the monitor facility to run the gpsd instance within
       gpsfake under control of gdb.

       The -o option 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 option 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 -r option specifies an initialization comand to use in pipe mode.
       The default is "w+r+"; "r=2" might be another interesting value.

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

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

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

       The -h option 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


       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.


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


       Eric S. Raymond There is a project page for gpsd


        1. here