Provided by: gpsd-clients_3.22-4.1_amd64 bug


       gpsfake - test harness for gpsd, simulating a GPS


       gpsfake [-?] [--baton] [--cycle interval] [--gdb] [--help] [--initcmd initcmd]
               [--linedump] [--lldb] [--monitor monitor] [--nowait] [--options=options] [--pipe]
               [--port port] [--predump] [--promptme] [--quiet] [--singleshot] [--slow]
               [--speed speed] [--tcp] [--timeout timeout] [--udp] [--verbose] [--version] [-1]
               [-b] [-c interval] [-D debuglevel] [-g] [-G] [-h] [-i] [-l] [-m monitor] [-n]
               [-o=options] [-p] [-P port] [-q] [-r initcmd] [-S] [-s speed] [-t] [-T] [-u] [-v]
               [-V] [-W timeout] [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.


       -?, -h, --help
           Print a usage message and exit.

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

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

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

       -d LVL, --debug LVL
           Pass a -D option to the daemon: thus -D 4 is shorthand for -o="-D 4".

       -g, -G, --gdb, --lldb
           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 or
           --wait . If xterm and $DISPLAY are available, these options launch the debugger in a
           separate xterm window, to separate the debugger dialog from the program output, but
           otherwise run it directly. In the gdb case, -tui is used with xterm but not otherwise,
           since curses and program output don't play nicely together. Although lldb lacks an
           equivalent option, some versions have a 'gui' command.

       -i, --promptme
           Single-step 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.

       -l, --linedump
           Print 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 printed as well. If not, the packet will
           be printed 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.

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

       -n, --nowait
           Pass -n to the daemon to start the daemon reading the GPS without waiting for a client
           (equivalent to -o="-n").

       -o="OPTS", --option="OPTS"
           Specify options to pass to the daemon. The equal sign (=) and quotes are required so
           that gpsd options are not confused with gpsfake options. To start the daemon reading
           the GPS without waiting for a client use -o="-n" (equivalent to the -n) which passes
           -n to the gpsd daemon. The option -o="-D 4" passes a -D 4 to the daemon, equivalent to
           the using -D 4.

       -p, --pipe
           Sets watcher mode and dump the NMEA and GPSD notifications generated by the log to
           standard output. This is useful for regression-testing.

       -p PORT, --port PORT
           Sets the daemon's listening port to PORT.

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

       -r STR, --clientinit STR
           Specify an initialization command to use in pipe mode. The default is

       -s SPEED, --speed SPEED
           Sets the baud rate for the slave tty. The default is 4800.

       -S, --slow
           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 load and possible race conditions in the pty

       -t, --tcp
           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 out.

       -T, --sysinfo
           Makes gpsfake print some system information and then exit.

       -u, --udp
           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 out.

       -v, --verbose
           Enable verbose progress reports to stderr. Use multiple times to increase verbosity.
           It is mainly useful for debugging gpsfake itself.

       -w SEC, --wait SEC
           Set 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.

       -x, --predump
           Dump packets as gpsfake gathers them. It is mainly useful for debugging gpsfake

       The last argument(s) must be the name of a file or files 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 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

           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

       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

       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


       For unknown reasons gpsfake may sometimes time out and fail. Set the WRITE_PAD environment
       value to a larger value to avoid this issue. A starting point might be "WRITE_PAD =
       0.005". Values as large os 0.200 may be required.


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


       Eric S. Raymond <>.