- Maintains GRASS Addons extensions in local GRASS installation.
Downloads and installs extensions from GRASS Addons repository or other source into the local GRASS installation or removes installed extensions.
g.extension [-lcgasdiftoj] extension=name operation=string [url=url] [prefix=path] [proxy=proxy[,proxy,...]] [branch=branch] [--help] [--verbose] [--quiet] [--ui]
- List available extensions in the official GRASS GIS Addons repository
- List available extensions in the official GRASS GIS Addons repository including module description
- List available extensions in the official GRASS GIS Addons repository (shell script style)
- List locally installed extensions
- Install system-wide (may need system administrator rights)
- Download source code and exit
- Do not install new extension, just compile it
- Force removal when uninstalling extension (operation=remove)
- Operate on toolboxes instead of single modules (experimental)
- url refers to a fork of the official extension repository
- Generates JSON file containing the download URLs of the official Addons
- Print usage summary
- Verbose module output
- Quiet module output
- Force launching GUI dialog
- extension=name [required]
- Name of extension to install or remove
- Name of toolbox (set of extensions) when -t flag is given
- operation=string [required]
- Operation to be performed
- Options: add, remove
- Default: add
- URL or directory to get the extension from (supported only on Linux and Mac)
- The official repository is used by default. User can specify a ZIP file, directory or a repository on common hosting services. If not identified, Subversion repository is assumed. See manual for all options.
- Prefix where to install extension (ignored when flag -s is given)
- Default: $GRASS_ADDON_BASE
- Set the proxy with: "http=<value>,ftp=<value>"
- Specific branch to fetch addon from (only used when fetching from git)
downloads and installs, removes or updates
extensions (addons) from the official
GRASS GIS Addons repository
or from user-specified source code repositories into the local GRASS GIS
Two types of extensions are supported:
- Python scripts: they are installed without the need of compilation or (usually)
the need of special dependencies.
- Source code (mostly written in C programming language; may also be written
in C++, Fortran or other languages): while on MS-Windows systems the requested
GRASS GIS extension is downloaded pre-compiled from the GRASS GIS site, on Unix
based systems the installation is preceded by the automated download of the
extension's source code along with subsequent compilation and installation.
This requires a compiler environment to be present on the user's computer.
Re-running g.extension on an installed GRASS GIS Addon
extension re-installs the requested extension which may include
To bulk-update all locally installed GRASS GIS extensions,
GRASS GIS extensions are installed by g.extension
into a dedicated
The default is a directory for application data and settings inside
the user's home directory.
On GNU/Linux it is $HOME/.grass8/addons
on MS-Windows it is %APPDATA%\Roaming\GRASS8\addons
The name of the directory is stored in the GRASS_ADDON_BASE
The flag -s changes this install target directory to the GRASS GIS
(determined by GISBASE environmental variable, e.g. /usr/)
rather than the default directory defined as per GRASS_ADDON_BASE
(see also documentation for variables).
g.extension checks if the user has permission to write to
GISBASE or GRASS_ADDON_BASE.
The place where the extensions are installed can be customized by
the option prefix. Ensuring that these extensions will be accessible
in GRASS GIS is in this case in the responsibility of the user.
GRASS GIS Addons repository on GitHub
By default, g.extension
installs extensions from the official
GRASS GIS Addons GitHub repository. However, different sources can be specified
using the url
Individual extensions can also be installed by providing a URL to the
source code on GitHub or OSGeo Trac. The latter, however, works only for certain
directories where the download of ZIP files was enabled by project administrators
of the trac server.
Local source code directory
Optionally, new extension can be also installed from a source code placed
in a local directory on disk. This is advantageous when developing
a new module.
To keep the directory clean, the directory content is copied
to a temporary directory and the compilation happens there.
Local source code ZIP file
In addition, new extension can be also installed from a ZIP file
or an archive file from the TAR family (e.g., .tar.gz
The file can be on disk (specified with a path), or on web (specified by
Online repositories: GitHub, GitLab and Bitbucket
For well known general hosting services, namely GitHub, GitLab and Bitbucket,
supports the download of a repository as a ZIP file.
Here the user only needs to provide a base URL to the repository web page
(with or without the https://
For GitLab and Bitbucket, the latest source code in the default branch is
downloaded, for GitHub, the latest source code in the master branch is downloaded.
Of course, a user can still specify the full URL of a ZIP file
and install a specific branch or release in this way (ZIP file mechanism
will be applied).
For the official repository, g.extension supports listing available
extensions (addons) and few other metadata-related operations which
depend on a specific infrastructure.
For other sources and repositories, this is not supported because it is
assumed that other sources contain only one extension, typically a module
or group of modules.
Needed directory layout
When none of the above sources is identified, g.extension
that the source is in a GitHub repository and uses the svn
line tool to obtain the source code. The expected structure of the repository
should be the same as the one of the official repository.
Non-official sources are supported on all operating systems except for
On MS-Windows systems, where compilation tools are typically not readily
locally installed, g.extension
downloads a precompiled executable
from the GRASS GIS project server. On all other operating systems
where it is not difficult to install compilation tools,
downloads the source code of the requested
extension (addon) and compiles it locally.
This applies for both C and Python modules
as well as any other extensions. The reason is that more things such
as manual page are compiled, not only the source code (which is really
necessary to compile just in case of C).
Download and install r.stream.distance
into current GRASS installation
This installs the extension from the official repository.
For convenience, a shorter syntax can be used:
Example for an open http proxy:
# syntax: http://proxyurl:proxyport
g.extension extension=r.stream.distance proxy="http=http://proxy.example.com:8080"
Example for a proxy with proxy authentication:
# syntax: http://username:password@proxyurl:proxyport
g.extension extension=r.stream.distance proxy="http=http://username:email@example.com:8080"
List all available extensions in the official GRASS GIS Addons repository:
List all locally installed extensions:
Removal of a locally installed extension:
g.extension extension=r.stream.distance operation=remove
Simple URL to GitHub, GitLab, Bitbucket repositories:
g.extension r.example.plus url="https://github.com/wenzeslaus/r.example.plus"
Simple URL to GitHub, GitLab, Bitbucket repositories from a specific (e.g. development) branch:
g.extension r.example.plus url="https://github.com/wenzeslaus/r.example.plus" branch=master
Simple URL to OSGeo Trac (downloads a ZIP file, requires download to be enabled in Trac):
g.extension r.example url=trac.osgeo.org/.../r.example
In general, when a ZIP file or other archive is provided, the full URL can be used:
g.extension r.example url=http://example.com/.../r.example?format=zip
Note that because of MS-Windows operating system architecture,
only official repository is supported on this platform.
To install a specific version from GRASS GIS Addons, specify the full
URL pointing to Trac code browser and include Subversion revision
number. For example, this installs the version number 57854 of
g.extension r.local.relief url="https://trac.osgeo.org/grass/browser/grass-addons/grass7/raster/r.local.relief?rev=57854&format=zip"
Having source code of a GRASS module in a directory on disk
one can install it using:
g.extension r.example url=/local/directory/r.example/
Toolboxes in the official repository cannot be downloaded.
On MS-Windows, only the official repository is working
because there is no way of compiling the modules
(a Python replacement for Python scripts should be implemented).
Since extensions have to be compiled on Unix based systems (Linux, Mac OSX etc.)
unless a Python extension is installed, a full compiler environment must be
present on the user's computer.
While GRASS GIS is available on the user's computer, the respective development
package is lacking. If GRASS was installed from a (Linux) repository, also the
grass-dev* package (commonly named "grass-dev" or "grass-devel", sometimes along
with the version number) must be installed.
GRASS GIS 8 Addons Manual pages
GRASS Addons wiki page.
Markus Neteler (original shell script)
Martin Landa, Czech Technical University in Prague, Czech Republic (Python rewrite)
Vaclav Petras, NCSU OSGeoREL
(support for general sources, partial refactoring)
g.extension source code
Latest change: Thu Feb 3 11:10:06 2022 in commit: 73413160a81ed43e7a5ca0dc16f0b56e450e9fef
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GRASS Development Team,
GRASS GIS 8.0.3dev Reference Manual