GPSFAKE(1) GPSD Documentation GPSFAKE(1)NAMEgpsfake - test harness for gpsd, simulating a GPS
SYNOPSISgpsfake [-1] [-h] [-b] [-f] [-c interval] [-i] [-D debuglevel] [-l]
[-m monitor] [-n] [-o options] [-p] [-P port] [-r initcmd]
[-s speed] [-u] [-v] [logfile...]
DESCRIPTIONgpsfake 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.
OPTIONS
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.
CUSTOM TESTSgpsfake 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
SEE ALSOgpsd(8), gps(1), libgps(3), libgpsd(3), gpsctl(1), gpspipe(1),
gpsprof(1)gpsmon(1).
AUTHOR
Eric S. Raymond <esr@thyrsus.com>.
The GPSD Project 12 Feb 2005 GPSFAKE(1)
