Provided by: grass-doc_7.8.2-1build3_all 
NAME
g.extension - 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.
KEYWORDS
general, installation, extensions, addons, download
SYNOPSIS
g.extension
g.extension --help
g.extension [-lcgasdift] extension=name operation=string [url=url] [prefix=path]
[proxy=proxy[,proxy,...]] [--help] [--verbose] [--quiet] [--ui]
Flags:
-l
List available extensions in the official GRASS GIS Addons repository
-c
List available extensions in the official GRASS GIS Addons repository including module description
-g
List available extensions in the official GRASS GIS Addons repository (shell script style)
-a
List locally installed extensions
-s
Install system-wide (may need system administrator rights)
-d
Download source code and exit
-i
Do not install new extension, just compile it
-f
Force removal when uninstalling extension (operation=remove)
-t
Operate on toolboxes instead of single modules (experimental)
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog
Parameters:
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=url
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=path
Prefix where to install extension (ignored when flag -s is given)
Default: $GRASS_ADDON_BASE
proxy=proxy[,proxy,...]
Set the proxy with: "http=<value>,ftp=<value>"
DESCRIPTION
g.extension 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 installation.
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.
Managing installed extensions
Re-running g.extension on an installed GRASS GIS Addon extension re-installs the requested extension
which may include updates.
To bulk-update all locally installed GRASS GIS extensions, g.extension.all module is available.
Where the extensions are installed
GRASS GIS extensions are installed by g.extension into a dedicated directory. The default is a directory
for application data and settings inside the user’s home directory. On GNU/Linux it is
$HOME/.grass7/addons, on MS-Windows it is $APPDATA\GRASS7\addons. The name of the directory is stored in
the GRASS_ADDON_BASE environmental variable.
The flag -s changes this install target directory to the GRASS GIS installation directory (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.
Source code sources and repositories
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 option.
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 or .bz2). The file can be on disk (specified with a path), or on web (specified by an
URL).
Online repositories: GitHub, GitLab and Bitbucket
For well known general hosting services, namely GitHub, GitLab and Bitbucket, g.extension 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:// part). 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 assumes that the source is in a GitHub
repository and uses the svn command 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 MS-Windows.
Compilation and installation
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, g.extension 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).
EXAMPLES
Download and install of an extension
Download and install r.stream.distance into current GRASS installation
g.extension extension=r.stream.distance
This installs the extension from the official repository. For convenience, a shorter syntax can be used:
g.extension r.stream.distance
Download and install of an extension when behind a proxy
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:password@proxy.example.com:8080"
Managing the extensions
List all available extensions in the official GRASS GIS Addons repository:
g.extension -l
List all locally installed extensions:
g.extension -a
Removal of a locally installed extension:
g.extension extension=r.stream.distance operation=remove
Installing from various online repositories: GitHub, GitLab, Bitbucket
Simple URL to GitHub, GitLab, Bitbucket repositories:
g.extension r.example url=github.com/johnsmith/r.example
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.
Install a specific version from Addons
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
r.local.relief module:
g.extension r.local.relief url="https://trac.osgeo.org/grass/browser/grass-addons/grass7/raster/r.local.relief?rev=57854&format=zip"
Installing when writing a module locally
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/
KNOWN ISSUES
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).
TROUBLESHOOTING
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.
ERROR: Please install GRASS development package
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.
SEE ALSO
g.extension.all
GRASS GIS 7 Addons Manual pages
GRASS Addons wiki page.
AUTHORS
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)
SOURCE CODE
Available at: g.extension source code (history)
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© 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual