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27.8. Using processing from the command line

QGIS comes with a tool called QGIS Processing Executor which allows you to run Processing algorithms and models (built-in or provided by plugins) directly from the command line without starting QGIS Desktop itself.

From a command line tool, run qgis_process and you should get:

QGIS Processing Executor - 3.27.0-Master 'Master' (3.27.0-Master)
Usage: C:\OSGeo4W\apps\qgis-dev\bin\qgis_process.exe [--help] [--version] [--json] [--verbose] [--no-python] [command] [algorithm id, path to model file, or path to Python script] [parameters]

Options:

  --help or -h      Output the help
  --version or -v   Output all versions related to QGIS Process
  --json            Output results as JSON objects
  --verbose         Output verbose logs
  --no-python       Disable Python support (results in faster startup)

Available commands:

  plugins          list available and active plugins
  plugins enable   enables an installed plugin. The plugin name must be specified, e.g. "plugins enable cartography_tools"
  plugins disable  disables an installed plugin. The plugin name must be specified, e.g. "plugins disable cartography_tools"
  list             list all available processing algorithms
  help             show help for an algorithm. The algorithm id or a path to a model file must be specified.
  run              runs an algorithm. The algorithm id or a path to a model file and parameter values must be specified.
                   Parameter values are specified after -- with PARAMETER=VALUE syntax.
                   Ordered list values for a parameter can be created by specifying the parameter multiple times,
                   e.g. --LAYERS=layer1.shp --LAYERS=layer2.shp
                   Alternatively, a '-' character in place of the parameters argument indicates that the parameters should be read from STDIN as a JSON object.
                   The JSON should be structured as a map containing at least the "inputs" key specifying a map of input parameter values.
                   This implies the --json option for output as a JSON object.
                   If required, the ellipsoid to use for distance and area calculations can be specified via the "--ELLIPSOID=name" argument.
                   If required, an existing QGIS project to use during the algorithm execution can be specified via the "--PROJECT_PATH=path" argument.

Notă

Only installed plugins that advertise hasProcessingProvider=yes in their metadata.txt file are recognized and can be activated or loaded by qgis_process tool.

Sugestie

Before calling qgis_process on a system without window manager (e.g. a headless server), you should set:

export QT_QPA_PLATFORM=offscreen

The command list can be used to get a list of all available providers and algorithms.

qgis_process list

The command help can be used to get further information about commands or algorithms.

qgis_process help qgis:regularpoints

The command run can be used to run an algorithm or model. Specify the name of the algorithm or a path to a model as first parameter.

qgis_process run native:buffer -- INPUT=source.shp DISTANCE=2 OUTPUT=buffered.shp

Acolo unde un parametru acceptă o listă de valori, setați aceeași variabilă de mai multe ori.

qgis_process run native:mergevectorlayers -- LAYERS=input1.shp LAYERS=input2.shp OUTPUT=merged.shp

While running an algorithm a text-based feedback bar is shown, and the operation can be cancelled via CTRL+C.

The run command also supports further parameters.

  • --json va formata rezultatul stdout într-un mod structurat JSON.

  • --ellipsoid va seta elipsoidul la cel specificat.

  • --distance_units va folosi unitățile de distanță specificate.

  • --area_units va folosi unitățile de suptafață specificate.

  • --project_path va încărca proiectul specificat pentru rularea algoritmului.

Parametrii de intrare complecși, adică tipurile de parametri care sunt ele însele specificate ca obiecte de tip dicționar pentru algoritmi, sunt acceptați de qgis_process. Pentru a indica faptul că parametrii vor fi specificați prin stdin, comanda qgis_process trebuie să urmeze formatul (cu un - la final, în locul listei obișnuite de argumente).

qgis_process run algorithmId -

The JSON object must contain an „inputs” key, which is a map of the input parameter values. E.g.

echo "{'inputs': {'INPUT': 'my_shape.shp', 'DISTANCE': 5}}" | qgis_process run native:buffer -

Additionally, extra settings like the distance units, area units, ellipsoid and project path can be included in this JSON object:

{
 'ellipsoid': 'EPSG:7019',
 'distance_units': 'feet',
 'area_units': 'ha',
 'project_path': 'C:/temp/my_project.qgs'
 'inputs': {'DISTANCE': 5, 'SEGMENTS': 8 ... }
}

Specifying input parameters via stdin implies automatically the JSON output format for results.