<command>#

The <command> tag represents an action within FlightGear XML files. It is typically used as a child element, such as in <binding>, to map an action to a user input (e.g., a keyboard key or joystick button).

Because of the large number of values that can be passed to the <command> element, it is quite a powerful command that is used across many different aspects of the simulator.

open-browser#

Description: The open-browser command is used to open a URL in the users web browser, typically for providing easy access to online documentation.

Syntax:

<binding>
  <command>open-browser</command>
  <path></path>
</binding>

<binding>
  <command>open-browser</command>
  <url></url>
</binding>

null#

Description: The null command does nothing. It is useful when no action is required.

Syntax:

<command>null</command>

—

exit#

Description: The exit command exits the simulator when triggered.

Syntax:

<command>exit</command>

—

pause#

Description: The pause command pauses the simulator when triggered.

Syntax:

<command>pause</command>

—

nasal#

Description: The nasal command triggers execution of Nasal code.

Usage:

A <script> element must be used alongside the <command> element. The <script> element must be provided a value containing the Nasal code to be executed.

Syntax:

<command>nasal</command>

Example:

<binding>
    <command>nasal</command>
    <script>print("Hello from Nasal!")</script>
</binding>
load - load properties from an XML file
file: the name of the file to load, relative to the current

directory (defaults to “fgfs.sav”)

save - save properties to an XML file
file: the name of the file to save, relative to the current

directory (defaults to “fgfs.sav”).

loadxml - load XML file into property tree

filename: the path & filename of the file to load targetnode: the target node within the property tree where to store the XML file’s structure. If targetnode isn’t defined, then the data will be stored in a node “data” under the argument branch.

savexml - save property tree node to XML file

filename: the path & filename for the file to be saved sourcenode: the source node within the property tree where the XML file’s structure is assembled from. If sourcenode isn’t defined, then savexml will try to save data stored in a node “data” in the argument branch.

panel-load - (re)load the 2D instrument panel
path: the path of the XML panel file, relative to $FG_ROOT (defaults

to the value of /sim/panel/path if specified, or “Panels/Default/default.xml” as a last resort.

preferences-load - (re)load preferences
path: the file name to load preferences from, relative to $FG_ROOT.

Defaults to “preferences.xml”.

view-cycle#

Description: The view-cycle command cycles to the next view, for example, changing from the “Helicopter View” to the “Chase View”.

screen-capture - capture the screen to a file

tile-cache-reload - reload the scenery tile cache

property-toggle#

Description: The property-toggle command toggles a boolean property value - if the property was previously false, it will be toggled to true, and vice-versa.

Usage: When a <command> element is passed a value of property-toggle, there must be an accompanying <property> element to indicate the property that should be toggled.

Example:

One common usecase for the property-toggle command is in the creation of bindings for input devices such as joysticks. Assuming we are creating an XML configuration for an input device, and wanted to create a binding that would toggle the parking brake, the XML would look like:

<binding>
  <command>property-toggle</command>
  <property>/controls/gear/brake-parking</property> <!-- Note the included property element -->
</binding>

property-assign#

Description: The property-assign command pauses the simulator when triggered.

  • assign a value to a property

property[0]: the name of the property that will get the new value. value: the new value for the property; or property[1]: the name of the property holding the new value.

property-interpolate#

Description: The property-interpolate command pauses the simulator when triggered.

  • assign a value to a property, interpolated

    over time

property[0]: the name of the property that will get the new value

and defines the starting point of the interpolation

value: the new value for the property; or property[1]: the name of the property holding the new value. time: the time in seconds it takes for the transition from the

old value to the new value of property[0]; or

rate: the ammount of change per second the value of property[0] changes

to transition to the new value

property-adjust#

Description: The pause command pauses the simulator when triggered.

  • adjust the value of a property

property: the name of the property to increment or decrement step: the amount of the increment or decrement (defaults to 0) offset: input offset distance (used for the mouse; multiplied by

factor)

factor: factor for multiplying offset distance (used for the mouse;

defaults to 1)

min: the minimum allowed value (default: no minimum) max: the maximum allowed value (default: no maximum) mask: ‘integer’ to apply only to the left of the decimal point;

‘decimal’ to apply only to the right of the decimal point; ‘all’ to apply to the full value (defaults to ‘all’)

wrap: true if the value should be wrapped when it passes min or max;

both min and max must be specified (defaults to false)

property-multiply#

Description: The pause command pauses the simulator when triggered.

  • multiply the value of a property

property: the name of the property to multiply factor: the amount by which to multiply (defaults to 1.0) min: the minimum allowed value (default: no minimum) max: the maximum allowed value (default: no maximum) mask: ‘integer’ to apply only to the left of the decimal point;

‘decimal’ to apply only to the right of the decimal point; ‘all’ to apply to the full value (defaults to ‘all’)

wrap: true if the value should be wrapped when it passes min or max;

both min and max must be specified (defaults to false)

property-swap#

Description:

property-scale#

Description:

property-cycle#

Description:

dialog-show#

Description:

dialog-close#

Description:

dialog-update#

Description:

dialog-apply#

Description:

presets-commit - commit preset values from /sim/presets

Attribution

Based on documentation originally created by David Megginson