Note: A new GRASS GIS stable version has been released: GRASS GIS 7. Go directly to the new manual page here
g.extension - Tool to maintain GRASS extensions in local GRASS installation.
Downloads, installs extensions from GRASS Addons SVN repository into local GRASS installation or removes installed extensions.
g.extension [-lsu] [extension=name] [operation=name] svnurl=url [prefix=path] [--verbose] [--quiet]
- List available modules in the GRASS Addons SVN repository
- Install system-wide (may need system administrator rights)
- Install system-wide using sudo
- Verbose module output
- Quiet module output
- Name of extension to install/remove
- Operation to be performed
- Options: add,remove
- Default: add
- SVN Addons repository URL
- Default: http://svn.osgeo.org/grass/grass-addons/grass6
- Prefix where to install extension
- Default: $GRASS_ADDON_PATH
g.extension downloads community contributed addon modules from
the GRASS-addons Subversion repository (SVN) and installs them on the
local system. These include modules providing specialist functionality,
modules in development and beta testing, newly proposed modules,
experimental modules, and simple helper scripts. There are additional
code contributions in the SVN repository which are either incomplete or
complex to install and so not available through g.extension. The
addons repository acts in part as an incubation area, so the code there
may not be as polished and well reviewed as the core GRASS modules, or it
may not even work at all. All code is license-compatible with GRASS and
can be used, shared, and modified under the same Free-software terms.
You are both welcome and encouraged to contribute your own scripts there,
and so make them available via g.extension, if you feel they
would be useful to others.
Re-running the script for an installed GRASS addon module re-installs
the requested extension. This is a handy way to apply updates or rebuild
compiled modules after installing a new version of GRASS.
The default action is to install the files into the first directory
listed in the GRASS_ADDON_PATH environment variable. If that has not been
set it will default to ~/.grass6/addons/ on UNIX or
%APPDATA%\GRASS6\addons on MS Windows. With suitable
administrative permissions you can optionally install directly into the
main GRASS program directory ($GISBASE).
The wxGUI contains a graphical extension manager separate to this version
of g.extension. The wxGUI Extension Manager can be found in the
Settings menu. While they are generally interchangeable, this help
page describes the version of g.extension run from the GRASS
command line. If one method of installing the addon fails you might try
again with the other.
Help and man pages installed with the module will be available
through the g.manual module.
If your GRASS_ADDON_PATH environment variable contains more than one
path, the default action is to use the first directory in the list.
Custom user scripts and installed addons can share the same addons
Note: Bourne shell and Python scripts run within
GRASS that use the g.parser module must be in the system's
search PATH, or else g.parser will not be able to find them and
complain about a failure to obtain the module's interface description. As
long as the GRASS_ADDON_PATH environment variable is set before
you start GRASS this will be taken care of automatically at startup.
For users building all of GRASS from source code who have also checked
out the GRASS-addons Subversion repository, an alternate approach is to
cd into the addon module's source directory, then run:
UNIX users can set up an alias in their ~/.bash_aliases file:
alias gmake643='make MODULE_TOPDIR=/path/to/grass643/source'
Users with GRASS installed from a GNU/Linux package can build without the
full GRASS source code installed, but they will need the associated
grass-dev and grass-doc packages installed.
Upgrading the GRASS version and users with multiple versions of GRASS
installed on the same system require special care when dealing with
compiled addon modules (those written in C and C++ and linking to
the GRASS C libraries). If you try to run a compiled C addon module which
was built using a different version of GRASS, you will get an error that
the module can not find the shared GIS libraries of the other version, or
if it can find them it will still check the internal versions and exit
with an error if they do not match. In these cases you can simply re-run
g.extension to rebuild the module and solve the problem.
You can typically share a single GRASS_ADDON_PATH directory for Bourne
shell scripts and Python addon modules written for any version of GRASS
6. Since your Addon modules and scripts will typically be in your user's
home directory and thus persist even when GRASS is upgraded or
reinstalled, some notes on compatibility:
- Forward compatibility: Any script written for GRASS 6.0 or newer
should work without changes with any newer version of GRASS 6. Module
names, options, and flag behavior will be respected for the life of the
stable release series.
- Backwards compatibility: Scripts written for newer versions of GRASS
6.4 may not work with earlier versions of GRASS 6 if they use commands
which were introduced later in the series. Other than that, they should
- API compatibility: While GRASS 6's core C library API is reasonably
stable (at time of writing it has not changed in 16 months) it is not
guaranteed. ABI compatibility is typically not maintained and compiled C
and C++ modules will need to be recompiled after an upgrade in GRASS
version. Changes to the source code should not be needed however, most
changes are simply the addition of new functionality and care has been
taken to avoid the repurposing or removal of old functions or libraries.
- The GRASS Python library: It is still in development, and Python 3
is just around the corner, so you can expect a few changes but starting
with GRASS 6.4.3 the core scripting library API is expected to remain
mostly stable. SWIG access to the GRASS C libraries has now been removed
and replaced by the ctypes library.
- Compatibility with GRASS 7: Not guaranteed. It is suggested to use a
separate directory for your GRASS 7 addons, or name your custom scripts
with the version number in the name. If you wish to write dual-compatible
scripts, the g.version module and GRASS_VERSION environment
variable are available for parsing at run-time.
Download and install i.landsat.toar into the current GRASS
This is a relatively new module and obtaining successful behavior on all
platforms is rather tricky. Please report any problems to the GRASS bug
tracker. If this automatic build fails, instructions for compiling both
the GRASS source code and GRASS addons by hand can be found in the GRASS
Note that Bourne shell and Python scripts can simply be downloaded from
the online Subversion repository browser and moved into your
GRASS_ADDON_PATH directory by hand. On UNIX you will likely need to set
the executable bit using chmod before the script will run.
In this case the associated usage section of the help page will not be
Installing addon Python scripts on MS Windows is still experimental and
is not guaranteed to work properly at run-time due to association of
".py" file extensions with python.exe. It is possible
to run them, but be aware that you will typically need to call them with
".py" as part of the module name.
Last changed: $Date: 2014-06-27 04:16:17 -0700 (Fri, 27 Jun 2014) $
Main index - general index - Full index
© 2003-2016 GRASS Development Team