Provided by: flightgear_2019.1.1+dfsg-1_amd64 bug

NAME

       fgfs - the FlightGear flight simulator

SYNOPSIS

       fgfs [options...]

DESCRIPTION

       fgfs  is  the  main  executable  for  FlightGear,  a free, open-source, multi-platform and
       sophisticated flight simulator framework for the development and  pursuit  of  interesting
       flight simulator ideas.

OPTIONS

       Options  are  first read from the command-line arguments passed to fgfs.  The program then
       checks for the existence of ~/.fgfsrc.hostname (where hostname  is  the  hostname  of  the
       machine)  and  of  ~/.fgfsrc; if at least one of those files exists, it is read and parsed
       (see the fgfsrc(5) man page for the full specifications of the file format).

       If conflicting options are given, the ones read last will prevail.

   General options
       --help, -h
              Display usage information about the most relevant command-line options and exit.

       --verbose, -v
              When combined with --help/-h, display  usage  information  about  all  command-line
              options, not just the most relevant ones.

       --version
              Display  version  information  about  fgfs  and  some  of the libraries used by the
              program (SimGear, OpenSceneGraph, PLIB), then exit.

       --fg-root=path
              Set the FlightGear data root directory ($FG_ROOT) to path. If this  option  is  not
              set,  fgfs  uses  the path specified in the FG_ROOT environment variable or, absent
              that, the FlightGear data directory chosen at the time the program was compiled.

       --fg-scenery=path
              Set the FlightGear scenery directories ($FG_SCENERY) to path.

              You can specify multiple directories by separating them  with  colons  (:),  as  in
              /first/path:/second/path  (on  Microsoft  Windows operating systems, multiple paths
              should be separated by semicolons instead): in that  case,  fgfs  will  follow  the
              order  the  paths are written in to search for scenery files, stopping as soon as a
              match is found.

              If this option is  not  set,  fgfs  uses  the  path  specified  in  the  FG_SCENERY
              environment variable or, absent that, the Scenery subdirectory inside $FG_ROOT.

       --fg-aircraft=path
              Load  additional  aircraft  from  path  besides  the  Aircraft  subdirectory inside
              $FG_ROOT. Alternatively, you can use --aircraft-dir to target a  specific  aircraft
              in a given directory.

       --download-dir=path
              Store aircraft and scenery downloaded via the simulator in path.

              The TerraSync directory may be specifically set with the --terrasync-dir option.

       --allow-nasal-read=dirs
              Allow  Nasal  aircraft  scripts  to  read files from the directories listed in dirs
              (separate multiple paths with colons, or semicolons on Microsoft Windows  operating
              systems).

              By default, Nasal scripts are allowed to read data only from $FG_ROOT and $FG_HOME,
              as a security measure.

       --read-only
              Make $FG_HOME (the location where user-specific FlightGear data  is  stored)  read-
              only.

       --language=code
              Set  the  language  used  by the simulator to code, where code is an ISO 639-1 two-
              letter locale code (for example, en or it).

       --restore-defaults
              Reset all user settings to their defaults.

       --enable-save-on-exit, --disable-save-on-exit
              Save/do not save user settings when the program exits.

       --ignore-autosave
              Ignore the user settings saved the previous time FlightGear was  run.  This  option
              implies --disable-save-on-exit.

       --browser-app=path
              Use the Web browser specified in path to open aircraft documentation.

       --prop:[type:]name=value
              Set  the  property  name  to value. You can optionally specify the property type by
              setting type to string, double, float, long, int or bool.

       --config=path
              Load additional configuration directives from path.  The  file  should  follow  the
              format described in fgfsrc(5).

       --no-default-config
              Do  not  load  any  configuration  files unless they were explicitly specified with
              --config.

       --units-feet
              Use feet as the internal measure unit for distances.

       --units-meters
              Use meters as the internal measure unit for distances.

       --console
              Display a console window for simulator/aircraft debugging purposes.

              This option is recognized only on Microsoft Windows  operating  systems;  on  other
              systems, debug messages are always printed to standard output/standard error.

       --launcher
              Start the FlightGear Launcher, a graphical Qt-based interface to the simulator.

              This option is available only if FlightGear was compiled with Qt support enabled.

       --json-report
              Print  a  report in JSON format on the standard output. The report will give useful
              information  for  debugging  purposes,  such  as  the   FlightGear   version,   the
              scenery/aircraft  paths in use, the TerraSync and the data download directories and
              the paths to navigation data files.

   Features
       --enable-panel, --disable-panel
              Enable/disable the pop-up aircraft instrument panel if the chosen airplane has it.

       --enable-hud, --disable-hud
              Enable/disable the heads-up display (HUD) if the chosen airplane has it.

       --enable-anti-alias-hud, --disable-anti-alias-hud
              Enable/disable heads-up display antialiasing.

       --enable-hud-3d, --disable-hud-3d
              Enable/disable the 3D version of the heads-up display.

       --hud-tris
              Display the number of triangles rendered when painting the heads-up display.

       --hud-culled
              Display the number of triangles culled when painting the heads-up display.

       --enable-random-objects, --disable-random-objects
              Show/hide random scenery objects,  such  as  buildings.  Scenery  objects  increase
              realism, but require more resources (memory and graphic card power).

       --enable-random-vegetation, --disable-random-vegetation
              Show/hide random vegetation.

       --enable-random-buildings, --disable-random-buildings
              Show/hide random buildings.

       --enable-ai-models, --disable-ai-models
              Enable/disable the internal AI subsystem, which is required for multiplayer gaming,
              AI traffic and many other  animations.  Disabling  the  internal  AI  subsystem  is
              deprecated.

       --enable-ai-traffic, --disable-ai-traffic
              Enable/disable artificial plane traffic.

       --ai-scenario=scenario
              Add and enable the AI scenario scenario. This option may be repeated multiple times
              to enable multiple scenarios.

       --enable-freeze
              Start the simulator in a frozen (paused) state.

       --disable-freeze
              Start the simulator in a running (unpaused) state.

       --enable-fuel-freeze
              Do not consume any fuel (keep its quantity in the tanks constant).

       --disable-fuel-freeze
              Consume fuel normally.

       --enable-clock-freeze
              Do not let the clock advance while running the simulation.

       --disable-clock-freeze
              Let the clock advance normally.

       --failure=pitot|static|vacuum|electrical
              Fail the aircraft pitot, static, vacuum or electrical systems. This option  may  be
              repeated multiple times to fail more than one system.

       --load-tape=tape
              Load and replay the flight recorder tape tape.

   Audio options
       --show-sound-devices
              Show a list of available audio devices and exit.

       --sound-device=name
              Set  the  sound  device  to use to name, where name is the device name shown by the
              --show-sound-devices option.

       --enable-sound, --disable-sound
              Enable/disable sound in the simulator.

   Rendering options
       --terrain-engine=tilecache|pagedLOD
              Choose the terrain engine to use. tilecache is  the  "traditional"  terrain  engine
              (recommended);  pagedLOD is a new, experimental terrain engine designed to minimize
              memory usage by loading more detailed versions of scenery objects on demand.

              The pagedLOD engine is available only if FlightGear was compiled with GDAL support.

       --lod-levels=levels
              Set the level of detail levels to levels, where levels is a space-separated list of
              numeric  levels.  This  option  is  available  only if the terrain engine in use is
              pagedLOD.

       --lod-res=resolution
              Set the terrain mesh resolution to resolution. This option is available only if the
              terrain engine in use is pagedLOD.

       --lod-texturing=bluemarble|raster|debug
              Set the terrain texture method. This option is available only if the terrain engine
              in use is pagedLOD.

       --lod-range-mult=multiplier
              Set the range multiplier (the breakpoint from a low to a high level of  detail)  to
              multiplier. This option is available only if the terrain engine in use is pagedLOD.

       --enable-rembrandt, --disable-rembrandt
              Enable/disable the Rembrandt engine ⟨http://wiki.flightgear.org/Project_Rembrandt⟩,
              which adds deferred shading  (rendering  all  properties  of  an  object,  such  as
              shading, lighting, fog) in more than one pass.

       --renderer=name
              If  the  Rembrandt  engine  is  enabled,  use  the  rendering pipeline described in
              $FG_ROOT/Effects/name.xml.

       --enable-splash-screen, --disable-splash-screen
              Show/hide the simulator splash screen while loading the aircraft/scenery.

       --enable-mouse-pointer, --disable-mouse-pointer
              Force enable display/do not force display the mouse pointer at startup.

       --max-fps=frequency
              Limit the maximum frame rate of the simulator to frequency Hz (frames per second).

       --bpp=depth
              Use a color depth of depth bits per pixel to display the aircraft and scenery.

       --fog-disable, --fog-fastest, --fog-nicest
              Choose the fog/haze  rendering  technique.   --fog-disable  will  disable  fog/haze
              entirely;  --fog-fastest will explicitly ask the graphics card driver to choose the
              most  efficient,  but  possibly  less  accurate,  fog/haze   rendering   algorithm;
              --fog-nicest  will  leave  the  algorithm  choice  to the driver, leading to higher
              quality results.

       --enable-enhanced-lighting, --disable-enhanced-lighting
              Enable/disable enhanced runway lighting. This option is deprecated.

       --enable-distance-attenuation, --disable-distance-attenuation
              Enable/disable runway light distance attenuation (the  runway  lights  become  less
              intense as distance increases).

       --enable-horizon-effect, --disable-horizon-effect
              Enable/disable the celestial body growth illusion near the horizon.

       --enable-specular-highlight, --disable-specular-highlight
              Enable/disable specular reflections on textured objects.

       --fov=degrees
              Set  the  field of view angle (FOV) to degrees. High field of view angles allow you
              to see a wider part of the world; low angles allow you to "zoom in" on details.

       --aspect-ratio-multiplier=factor
              Set the horizontal and vertical aspect ratio multiplier to factor.

       --enable-fullscreen, --disable-fullscreen
              Enable/disable fullscreen mode.

       --shading-flat, --shading-smooth
              Use flat/smooth shading. If flat shading is active, the  simulator  uses  the  same
              color  to  paint  the  face  of  an  object:  this  is faster, but makes edges more
              pronounced. Smooth shading smooths  color  changes  between  vertices,  leading  to
              higher-quality results, at an expense in performance.

       --materials-file=file
              Load  the  definitions  of  the  materials used to render the scenery from file. By
              default, materials are loaded from $FG_ROOT/regions/materials.xml.

       --texture-filtering=value
              Set the anisotropic texture  filtering  to  value.  The  acceptable  values  are  1
              (default), 2, 4, 8 or 16.

       --enable-wireframe, --disable-wireframe
              Enable/disable the wireframe drawing mode (in which only object edges are painted).

       --geometry=widthxheight
              Set  the  window  geometry  (size)  to  widthxheight  (both width and height are in
              pixels).

       --view-offset=LEFT|RIGHT|CENTER|value
              Specify the default forward view direction as an offset from straight  ahead.   The
              allowed  values  are  LEFT (-90°), RIGHT (90°), CENTER (0°) or a specific number in
              degrees.

   Aircraft options
       --aircraft=name, --vehicle=name
              Load an aircraft/vehicle from a set file named name-set.xml. The file  is  searched
              for  in  $FG_ROOT/Aircraft, in the directory pointed to by the environment variable
              FG_AIRCRAFT and in the  directories  passed  to  fgfs(1)  using  the  --fg-aircraft
              option.

       --aircraft-dir=path
              Explicitly specify the directory in which the -set.xml file should be searched for.
              If this argument is used, the path cache stored  in  ~/.fgfs/autosave_X_Y.xml,  the
              directories passed with the --fg-aircraft option and the directory specified in the
              FG_AIRCRAFT environment variable are not taken into account.

       --show-aircraft
              Print a list of available aircraft and exit.

       --min-status=alpha|beta|early-production|production
              Do not list aircraft having a status level (development status) lower than the  one
              specified.   See  the  FlightGear  wiki  "Aircraft  rating  system"  page  ⟨http://
              wiki.flightgear.org/Aircraft_rating_system⟩ for an extended description of aircraft
              ratings.

       --fdm=jsb|larcsim|yasim|magic|balloon|ada|external|null
              Select the core flight dynamics model to use among the following ones:

              ·  jsb:  the  JSBSim  flight dynamics model ⟨http://www.jsbsim.org/⟩, which takes a
                 data-driven approach to modeling: given the performance  data  for  an  aircraft
                 (mass and balance, ground reactions, propulsions, aerodynamics...), it assembles
                 it together to produce the global aircraft dynamics;

              ·  larcsim:  the  LaRCsim  flight  dynamics  model  ⟨http://www.jsbsim.org/⟩,   the
                 original model used in FlightGear up to 2000, developed at NASA, now inactive;

              ·  yasim:  the  YASim  flight  dynamics  model  ⟨http://wiki.flightgear.org/YASim⟩,
                 which, given the physical and flying characteristics of an aircraft, attempts to
                 solve for them;

              ·  magic: the "Magic Carpet" flight model;

              ·  balloon: a hot air balloon simulation;

              ·  ada:  an  externally-driven  flight  dynamics model designed by the Aeronautical
                 Development Agency of Bangalore, India;

              ·  external/null: use an external flight dynamics model (the  external  option  has
                 the same meaning as null and is maintained for backward compatibility purposes).

       --aero=name
              Load  the  aircraft  aerodynamics  model  from  the  file  name.xml in the aircraft
              directory.

       --model-hz=n
              Run the flight dynamics model at a frequency of n Hz (n times per second).

       --speed=n
              Run the flight dynamics model n times faster than real time.

       --trim, --notrim
              Trim/do not attempt to trim the model. This option is  only  valid  if  the  flight
              dynamics module in use is JSBSim.

       --on-ground
              Start the aircraft on the ground. This is the default option.

       --in-air
              Start the aircraft in the air. This option is implied if --altitude is specified.

       --enable-auto-coordination, --disable-auto-coordination
              Enable/disable auto coordination (joint control of rudder and ailerons).

       --livery=name
              Load the aircraft livery from a file named name.

       --state=value
              Set  the  initial  aircraft  state  to  value.  The  states  that  can  be used are
              aircraft-dependent.

   Time options
       --timeofday=real|dawn|morning|noon|afternoon|dusk|evening|midnight
              Start the simulator at the specified time of day:

              ·  real: real clock time;

              ·  dawn: the time when the Sun is 90° E on the horizon;

              ·  morning: the time when the Sun is 75° E on the horizon;

              ·  noon: the time when the Sun is 0° on the horizon;

              ·  afternoon: the time when the Sun is 75° W on the horizon;

              ·  dusk: the time when the Sun is 90° W on the horizon;

              ·  evening: the time when the Sun is 100° W on the horizon;

              ·  midnight: the time when the Sun is 180° on the horizon.

       --season=summer|winter
              Load summer/winter textures.

       --time-offset=[+|-]hh:mm:ss
              Add a time offset to the startup time specified with the --timeofday option.

       --time-match-real
              Synchronize the simulator time with real world GMT time.

       --time-match-local
              Synchronize the simulator time with real world local time.

       --start-date-sys=yyyy:mm:dd:hh:mm:ss
              Specify the simulator starting date and time with respect to the local timezone  of
              the system.

       --start-date-gmt=yyyy:mm:dd:hh:mm:ss
              Specify  the  simulator  starting  date and time with respect to the Greenwich Mean
              Time.

       --start-date-lat=yyyy:mm:dd:hh:mm:ss
              Specify the simulator starting date and time with respect to the  timezone  of  the
              starting airport.

   Initial position and orientation
       --airport=ID
              Start the simulator at the airport having ID as its ICAO code.

       --parking-id=name
              Place the aircraft at the parking position name. This option requires the --airport
              option to be present.

       --runway=number
              Place the aircraft on runway number. This option requires the --airport  option  to
              be present.

       --carrier=name|ID
              Place the aircraft on the AI carrier named name/having the ID ID.

       --parkpos=name
              Place  the  aircraft  at  the  starting  position  name.  This  option requires the
              --carrier option to be present.

       --vor=ID
              Place the aircraft over the VOR ID.

       --vor-frequency=frequency
              Set the frequency of the VOR to frequency. This option requires the --vor option to
              be present.

       --ndb=ID
              Place the aircraft over the NDB ID.

       --ndb-frequency=frequency
              Set the frequency of the NDB to frequency. This option requires the --ndb option to
              be present.

       --fix=ID
              Place the aircraft over the fix ID.

       --offset-distance=nm
              Place the aircraft nm statute miles away from the reference point specified by  the
              previous options.

       --offset-azimuth=degrees
              Place  the  aircraft  at a heading of degrees degrees with respect to the reference
              point specified by the previous options.

       --lon=degrees, --lat=degrees
              Place the aircraft  at  the  point  with  the  coordinates  (lat,  lon).   Northern
              longitudes/eastern   latitudes   must   be  positive;  southern  longitudes/western
              latitudes must be negative.

       --altitude=value
              Place the aircraft at an altitude of  value  feet  (meters  if  the  --units-meters
              option was specified).

       --heading=degrees
              Specify the initial heading (yaw) angle (psi) of the aircraft.

       --roll=degrees
              Specify the initial roll angle (phi) of the aircraft.

       --pitch=degrees
              Specify the initial pitch angle (theta) of the aircraft.

       --uBody=units_per_sec
              Specify the initial velocity along the body X axis.

       --vBody=units_per_sec
              Specify the initial velocity along the body Y axis.

       --wBody=units_per_sec
              Specify the initial velocity along the body Z axis.

       --vNorth=units_per_sec
              Specify the initial velocity along the body North-South axis.

       --vEast=units_per_sec
              Specify the initial velocity along the body West-East axis.

       --vDown=units_per_sec
              Specify the initial velocity along the body vertical axis.

       --vc=knots
              Set the initial airspeed of the aircraft to knots knots.

       --mach=number
              Set the initial airspeed of the aircraft to Mach number.

       --glideslope=degrees
              Set the flight path angle to degrees degrees. The value can be positive.

       --roc=fpm
              Set the initial rate of climb to fpm feet per minute. The value can be negative.

   Route/waypoint options
       --wp=ID[@alt]
              Enter  the  waypoint  (VOR, NDB, fix) ID into the autopilot. The optional part @alt
              can be used to specify the altitude at which ID should be crossed.

       --flight-plan=file
              Read a flight plan from file.

   Avionics options
       --com1=frequency
              Set the COM1 frequency to frequency MHz.

       --com2=frequency
              Set the COM2 frequency to frequency MHz.

       --nav1=[radial:]frequency
              Set the NAV1 frequency to frequency MHz. You can optionally  specify  a  radial  by
              prefixing the frequency with the heading and a colon.

       --nav2=[radial:]frequency
              Set  the  NAV2  frequency  to frequency MHz. You can optionally specify a radial by
              prefixing the frequency with the heading and a colon.

       --adf1=[rotation:]frequency, --adf=[rotation:]frequency
              Set the ADF1 frequency to frequency kHz. You can optionally  specify  the  rotation
              angle  of  its  compass card by prefixing the frequency with the angle and a colon.
              The --adf option is deprecated.

       --adf2=[rotation:]frequency
              Set the ADF2 frequency to frequency kHz. You can optionally  specify  the  rotation
              angle of its compass card by prefixing the frequency with the angle and a colon.

       --dme=nav1|nav2|frequency
              Slave  the  automatic  direction  finder to the NAV1/NAV2 radio or set its internal
              frequency to frequency.

   Environment options
       --metar=METAR
              Simulate the weather conditions described by the METAR string  METAR.  This  option
              implies --disable-real-weather-fetch.

       --enable-real-weather-fetch, --disable-real-weather-fetch
              Enable/disable  METAR-based  real weather fetching. This feature requires an active
              Internet connection.

       --enable-clouds, --disable-clouds
              Enable/disable 2D (flat) cloud layers.

       --enable-clouds3d, --disable-clouds3d
              Enable/disable 3D (volumetric) cloud layers.

       --visibility=meters
              Set the initial visibility to meters meters.

       --visibility-miles=miles
              Set the initial visibility to miles miles.

       --wind=dir[:maxdir]@speed[:gust]
              Specify the direction the wind blows from (dir) and its speed (speed knots). If the
              wind  is  not  meant  to  blow  from  a fixed direction, but rather from a range of
              directions, specify the range as dir:maxdir, where dir and maxdir are  the  minimum
              and  maximum  angles  in  degrees. If you want the simulator to model wind gusts as
              well, set gust to their maximum intensity in knots.

       --random-wind
              Randomize the direction and speed of the wind.

       --turbulence=intensity
              Set the turbulence intensity to intensity. The intensity can range from 0.0  (calm)
              to 1.0 (severe).

       --ceiling=ft_asl[:thickness_ft]
              Create an overcast ceiling at a height of ft_asl feet above the mean sea level. You
              can optionally specify a thickness  by  appending  a  colon  (:)  and  the  desired
              thickness in feet; if you omit it, the simulator will default to 2000 ft.

   Network options
       --callsign=value
              Set  the multiplayer callsign to value. The callsign must be at most ten characters
              long and must contain only numbers, letters of the English alphabet, dashes (-) and
              underscores  (_); longer callsigns are truncated, and characters not matching those
              listed above are replaced with dashes.

       --multiplay={in|out},hz,address,port
              Specify the multiplayer communication settings.

              The first field specifies whether the settings apply to inbound  (in)  or  outbound
              (out)  communications.  The second field (hz) specifies the frequency (in Hz, times
              per second) at which data should be sent. The third field (address) must be set  to
              the  IP address of the network interface that FlightGear should use to send/receive
              data, or left blank to let the simulator use all available interfaces.  The  fourth
              field (port) should be set to the port to use (usually 5000).

       --proxy=[username:password@]host:port
              Specify  the  proxy server and port to use. The username and password are optional;
              if they are present, they should be given as MD5 hashes.

              This option is only useful if --real-weather-fetch is enabled.

       --httpd=[address:]port
              Enable the Phi interface (HTTP server) on  the  specified  address  and  port.  The
              address is optional.

       --telnet=port
              Enable the Telnet interface on the specified port.

       --jpg-httpd=port
              Enable  the  screenshot HTTP server interface on the specified port. This option is
              deprecated: use the Phi interface instead.

       --enable-terrasync, --disable-terrasync
              Enable/disable automatic scenery/object downloads.

       --terrasync-dir=directory
              Set the directory where the downloaded scenery will be stored to directory.

       --enable-fgcom, --disable-fgcom
              Enable/disable the FGCom (voice ATC) integration.

   I/O options
       --generic=params,  --atlas=params,  --atcsim=params,  --AV400=params,   --AV400Sim=params,
       --AV400WSimA=params,       --AV400WSimB=params,       --garmin=params,       --hla=params,
       --hla-local=params,       --igc=params,       --joyclient=params,       --jsclient=params,
       --native-ctrls=params,    --native-gui=params,    --native-fdm=params,    --native=params,
       --nmea=params, --opengc=params, --props=params, --pve=params, --ray=params, --rul=params
              Open a connection to drive external programs or hardware.

              Specify the protocol by using the correct command-line option:

              ·  generic: a predefined communication interface and  a  preselected  communication
                 protocol;

              ·  atlas: the Atlas protocol;

              ·  atcsim: the ATCsim (atc610x) protocol;

              ·  AV400: the Garmin AV400 protocol, required to drive a Garmin 196/296 series GPS;

              ·  AV400Sim: the set of AV400 strings required to drive a Garmin 400-series GPS;

              ·  AV400WSimA,  AV400WSimB:  the set of strings required to drive a Garmin WAAS GPS
                 (where the A channel uses a variant of the AVSim400 protocol and the  B  channel
                 communicates with the GPS unit);

              ·  garmin: the Garmin GPS protocol;

              ·  hla, hla-local: the HLA protocol, either remote or local;

              ·  igc: the International Glider Commission protocol;

              ·  joyclient: the protocol used by Agwagon joysticks;

              ·  native-ctrls: the FlightGear Native Controls protocol;

              ·  native-gui: the FlightGear Native GUI protocol;

              ·  native-fdm: the FlightGear Native FDM protocol;

              ·  native: the FlightGear Native protocol;

              ·  nmea: the NMEA protocol (used to drive most GPS units);

              ·  opengc:  the  protocol  used  by  OpenGC, a software used to render high-quality
                 glass cockpit displays for simulated flightdecks;

              ·  props: the interactive property manager protocol;

              ·  pve: the PVE protocol;

              ·  ray: the Ray Woodworth motion chair protocol;

              ·  rul: the RUL protocol.

              The parameters (params) must  be  in  the  form  medium,direction,hz,medium_options
              where  medium  is  the  medium  used  by  the  protocol  (serial, socket, file...),
              direction is the communication direction (in, out or bi), hz is the  frequency  the
              channel   should   be  processed  at  (floating  point  values  are  accepted)  and
              medium_options are:

              ·  for serial protocols, device,baud, where device is the device name to be  opened
                 and baud is the communication baud rate;

              ·  for  socket  protocols, machine,port,style, where machine is the machine name or
                 the IP address of the server (if the simulator should act as  a  client)  or  is
                 left  empty  (if  the simulator should act as a server), port is the port to use
                 (or is left empty to ask the operating system to choose an available  port)  and
                 style is tcp or udp;

              ·  for file protocols, filename, where filename is the name of the file data should
                 be written to.

   Debugging options
       --enable-fpe
              Abort when a floating-point exception is encountered.

       --fgviewer
              View the scenery and the aircraft in a simple model  viewer,  without  loading  the
              entire simulator.

       --log-level=bulk|debug|info|warn|alert
              Set the minimum logging level. Log messages having a severity greater than or equal
              to the specified value are recorded; the others are discarded.

       --log-class=all|none|ai|environment|flight|general|io|network|sound|terrain|...
              Log only events belonging to the specified log classes (all logs all  events,  none
              logs  none).  Multiple  classes  can be specified by separating them with commas or
              pipes, for example: --log-class=ai,flight.

       --log-dir=dir
              Save the logs in the directory dir. If dir is desktop, the logs are  saved  on  the
              Desktop.  This  option may be given several times, using a different directory each
              time. Inside the specified directory, the log file will be  named  FlightGear_YYYY-
              MM-DD_num.log, where YYYY-MM-DD is the current date and num is a progressive number
              starting at 0.

       --trace-read=property, --trace-write=property
              Trace the reads/writes for a property (print a log  message  whenever  property  is
              read from/written to).

       --developer
              Enable developer mode.

EXIT STATUS

       fgfs exits with 0 if the execution completes successfully, or with another status (usually
       1 or -1) if an error occurred.

ENVIRONMENT

       COMPUTERNAME
           Specifies the hostname of the system in use. This environment variable is  only  taken
           into account on Microsoft Windows operating systems.

       FG_AIRCRAFT
           Specifies the path in which aircraft should be searched for.

       FG_LAUNCHER
           If  this  environment variable is set and is not 0, the Qt launcher will be shown. The
           variable is mainly used on Mac OS X operating systems to  avoid  the  use  of  wrapper
           scripts.

       FG_ROOT
           Specifies the root data directory to use.

       FG_SCENERY
           Specifies the scenery directory to use.

       HTTP_PROXY
           Specifies the HTTP proxy to use. Must be in the form http://host:port/.

       LANG
           Specifies the language to use.

FILES

       ~/.fgfs
           The   main  directory  where  FlightGear  configuration  files  and  data  (downloaded
           aircraft/scenery) are stored.

       ~/.fgfsrc.hostname, ~/.fgfsrc
           Configuration files containing command-line options for fgfs(1).