gpsfake [-1] [-h] [-b] [-f] [-c interval] [-i] [-D debuglevel] [-l] [-m monitor] [-g] [-n] [-o options] [-p] [-P port] [-r initcmd] [-s speed] [-u] [-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 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:
a comment of the form #Date: yyyy-mm-dd (ISO8601 date format) may be used to set the initial date for the log.
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 bits.
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 right.
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 uses the monitor facility to run the
gpsd instance within gpsfake under control
of gdb.
The -f configures gpsd to bind
to a random dynamic/private port (range 49152 - 65535). Its main use
is within regression-test scripts so they won't collide with a production
instance.
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 -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 -u forces the test framework to use UDP rather than
pty devices. This may be useful for testing from within chroot jails
where access to pty devices is locked out.
The -v enables verbose progress reports to stderr. It is
mainly useful for debugging gpsfake
itself.
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 cycles.
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 192.168.0.1.255. You can monitor them with this: tcpdump -s0 -n -A -i lo udp and port 5000.
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