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]
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
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
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),
Eric S. Raymond email@example.com. There is a project page for gpsd