Provided by: grass-doc_8.3.0-1_all 
GRASS startup program
SYNOPSIS
grass [-h | -help | --help] [-v | --version] | [-c | -c geofile | -c
EPSG:code[:datum_trans]] | -e | -f | [--text | --gtext | --gui] | --config |
[--tmp-location | --tmp-mapset] [[[<GISDBASE>/]<LOCATION>/] <MAPSET>] [--exec EXECUTABLE]
Flags:
-h | -help | --help
Prints a brief usage message and exits
-v | --version
Prints the version of GRASS and exits
-c
Creates new GRASS unprojected location in specified GISDBASE
-c geofile
Creates new GRASS projected location in specified GISDBASE based on georeferenced file
-c EPSG:code
Creates new GRASS projected location in specified GISDBASE with given EPSG code
-c EPSG:code:datum_trans
Creates new GRASS projected location in specified GISDBASE with given EPSG code and
datum transform parameters
-e
Exit after creation of location or mapset. Only with -c flag
-f
Forces removal of .gislock if exists (use with care!). Only with --text flag
--text
Indicates that Text-based User Interface should be used (skip welcome screen)
--gtext
Indicates that Text-based User Interface should be used (show welcome screen)
--gui
Indicates that Graphical User Interface (wxGUI) should be used
--config
Prints GRASS configuration parameters (options: arch, build, compiler, date, path,
python_path, revision, svn_revision, version)
--exec EXECUTABLE
Execute GRASS module or script. The provided executable will be executed in a GRASS
GIS non-interactive session.
--tmp-location
Run using a temporary location which is created based on the given coordinate
reference system and deleted at the end of the execution (use with the --exec flag).
The active mapset will be the PERMANENT mapset.
--tmp-mapset
Run using a temporary mapset which is created in the specified location and deleted at
the end of the execution (use with the --exec flag).
Parameters:
GISDBASE
Initial database directory which should be a fully qualified path (e.g.,
/usr/local/share/grassdata)
LOCATION
Initial location directory which is a subdirectory of GISDBASE
MAPSET
Initial mapset directory which is a subdirectory of LOCATION Note: These parameters
must be specified in one of the following ways:
MAPSET
LOCATION/MAPSET
GISDBASE/LOCATION/MAPSET
DESCRIPTION
This command is used to launch GRASS GIS. It will parse the command line arguments and
then initialize GRASS for the user. Since GRASS modules require a specific environment,
this program must be called before any other GRASS module can run. The command line
arguments are optional and provide the user with a method to indicate the desired user
interface, as well as the desired mapset to work on.
The startup program will remember both the desired user interface and mapset. Thus, the
next time the user runs GRASS, typing grass (without any options) will start GRASS with
the previous settings for the user interface and mapset selected.
If you specify a graphical user interface (--gui) the grass program will try to verify
that the system you specified exists and that you can access it successfully. If any of
these checks fail then grass will automatically switch back to the text user interface
mode.
Running non-interactive jobs
The --exec flag can run an executable on path, GRASS module, or a script. All are
executed as a subprocess and any additional arguments are passed to it. A script needs to
be specified by full or relative path and on unix-likes systems, the script file must have
its executable bit set. Calling the interpreter (e.g., python) and providing the script as
a parameter is possible, too. When it is finished GRASS will automatically exit using the
return code given by the subprocess. Although the execution itself is non-interactive (no
GUI or shell), the subprocess itself can be interactive if that is what the user requires.
Config flag
The flag --config option prints GRASS GIS configuration and version parameters, with the
options:
• arch: system architecture (e.g., x86_64-pc-linux-gnu)
• build: (e.g., ./configure --with-cxx --enable-largefile --with-proj [...])
• compiler: (e.g., gcc)
• date: (e.g., Tue Mar 31 20:34:57 2020 +0200)
• path: (e.g., /usr/lib64/grass)
• python_path: (e.g., /usr/lib64/grass/etc/python)
• revision: (e.g., 745ee7ec9)
• svn_revision: (e.g., 062bffc8)
• version: (e.g., 8.2.0dev)
SAMPLE DATA
The GRASS GIS project provides several free sample geospatial datasets as ready-to-use
locations. They are available to download at
https://grass.osgeo.org/download/sample-data/. The "North Carolina data set" is a modern
package of geospatial data from North Carolina (USA), and it includes raster, vector,
LiDAR and satellite data. This is the most extensively used data set in the documentation
and the examples throughout the user manual pages are based upon it.
ENVIRONMENT VARIABLES
A number of environment variables are available at GRASS startup to assist with automation
and customization. Most users will not need to bother with these.
In addition to these shell environment variables GRASS maintains a number of GIS
environment variables in the $HOME/.grass8/rc file. User changes to this file will be read
during the next startup of GRASS. If this file becomes corrupted the user may edit it by
hand or remove it to start afresh. See the list of implemented GRASS variables for more
information. The rest of this help page will only consider shell environment variables.
Note that you will need to set these variables using the appropriate method required for
the UNIX shell that you use (e.g. in a Bash shell you must export the variables for them
to propagate).
User Interface Environment Variable
The grass program will check for the existence of an environment variable called GRASS_GUI
which indicates the type of user interface for GRASS to use. If this variable is not set
when grass is run, then it will be created and then saved in the $HOME/.grass8/rc file for
the next time GRASS is run. It can be set to text, gtext or gui.
There is an order of precedence in the way grass determines the user interface to use. The
following is the hierarchy from highest precedence to lowest.
1 Command line argument
2 Environment variable GRASS_GUI
3 Value set in $HOME/.grass8/rc (GUI)
4 Default value - gui
Python Environment Variables
If you choose to use wxGUI interface, then the GRASS_PYTHON environment variable can be
used to override your system default python command.
Suppose for example your system has Python 3.6 installed and you install a personal
version of the Python 3.8 binaries under $HOME/bin. You can use the above variables to
have GRASS use the Python 3.8 binaries instead.
GRASS_PYTHON=python3.8
Addon Path to Extra User Scripts
This environment variable allows the user to extend the GRASS program search paths to
include locally developed/installed GRASS modules or user scripts.
GRASS_ADDON_PATH=/usr/mytools
GRASS_ADDON_PATH=/usr/mytools:/usr/local/othertools
In this example above path(s) would be added to the standard GRASS path environment.
Addon Base for Extra Local GRASS Addon Modules
This environment variable allows the user to extend the GRASS program search paths to
include locally installed (see g.extension for details) GRASS Addon modules which are not
distributed with the standard GRASS release.
GRASS_ADDON_BASE=/usr/grass-addons
In this example above path would be added to the standard GRASS path environment.
If not defined by user, this variable is set by GRASS startup program to
$HOME/.grass8/addons on GNU/Linux and %APPDATA%\Roaming\GRASS8\addons on MS Windows.
HTML Browser Variable
The GRASS_HTML_BROWSER environment variable allows the user to set the HTML web browser to
use for displaying help pages.
EXAMPLES
The following are some examples of how you could start GRASS
grass
Start GRASS using the default user interface. The user will be prompted to choose the
appropriate location and mapset.
grass --gui
Start GRASS using the graphical user interface. The user will be prompted to choose
the appropriate location and mapset.
grass --text
Start GRASS using the text-based user interface. Appropriate location and mapset must
be set by environmental variables (see examples below) otherwise taken from the last
GRASS session.
grass --gtext
Start GRASS using the text-based user interface. The user will be prompted to choose
the appropriate location and mapset.
grass $HOME/grassdata/spearfish70/user1
Start GRASS using the default user interface and automatically launch into the given
mapset, bypassing the mapset selection menu.
grass --gui -
Start GRASS using the graphical user interface and try to obtain the location and
mapset from environment variables.
grass -c EPSG:4326 $HOME/grassdata/mylocation
Creates a new GRASS location with EPSG code 4326 (latitude-longitude, WGS84) in the
specified GISDBASE
grass -c EPSG:5514:3 $HOME/grassdata/mylocation
Creates a new GRASS location with EPSG code 5514 (S-JTSK / Krovak East North - SJTSK)
with datum transformation parameters used in Czech Republic in the specified GISDBASE
grass -c XY $HOME/grassdata/gnomonic --exec g.proj -c proj4=’+proj=gnom +lat_0=90
+lon_0=-50’
Creates a new GRASS location from PROJ definition string (here: gnomonic) in the
specified GISDBASE
grass -c myvector.shp $HOME/grassdata/mylocation
Creates a new GRASS location based on georeferenced Shapefile
grass -c myraster.tif $HOME/grassdata/mylocation
Creates a new GRASS location based on georeferenced GeoTIFF file
Batch jobs with the exec interface
Creating a new Location based on a geodata file’s projection (-c) and exit (-e)
immediately:
grass -c elevation.tiff -e /path/to/grassdata/test1/
Linking external raster data to PERMANENT Mapset:
grass /path/to/grassdata/test1/PERMANENT/ --exec r.external input=basins.tiff output=basins
grass /path/to/grassdata/test1/PERMANENT/ --exec r.external input=elevation.tiff output=elevation
Get statistics for one raster map:
grass /path/to/grassdata/test1/PERMANENT/ --exec r.univar map=elevation
Compare the rasters visually:
grass /path/to/grassdata/test1/PERMANENT/ --exec g.gui.mapswipe first=elevation second=basins
Execution of shell and Python scripts instead of single commands
A sequence of commands can be bundled in a script and executed using the exec interface.
Shell script example: the command to execute a shell script might be:
grass /path/to/grassdata/test1/PERMANENT/ --exec sh test.sh
A very simple bash script ("test.sh") may look like this:
#!/bin/bash
g.region -p
g.list type=raster
r.info elevation
Python script example: the command to execute a Python script might be:
grass /path/to/grassdata/test1/PERMANENT/ --exec python test.py
A very simple Python script ("test.py") may look like this:
#!/usr/bin/env python3
# import GRASS Python bindings (see also pygrass)
import grass.script as gs
gs.message(’Current GRASS GIS environment:’)
print(gs.gisenv())
gs.message(’Available raster maps:’)
for raster in gs.list_strings(type=’raster’):
print(raster)
gs.message(’Available vector maps:’)
for vector in gs.list_strings(type=’vector’):
print(vector)
Using temporary location
Creating a new temporary location based on a georeferenced file’s projection coordinate
reference system (CRS) and simultaneously starting computation in a shell script:
grass --tmp-location elevation.tiff --exec test.sh
The same, but using an EPSG code and a Python script:
grass --tmp-location EPSG:3358 --exec test.py
Finally, for special cases, we can create an XY location without any CRS:
grass --tmp-location XY --exec test.py
Temporary location is automatically deleted after computation, so the script is expected
to export, link or otherwise preserve the output data before ending.
A single command can be also executed, e.g. to examine properties of the temporary
location:
grass --tmp-location EPSG:3358 --exec g.proj -p
A temporary XY location with single command is useful, e.g. to show help text of a module:
grass --tmp-location XY --exec r.neighbors --help
Using temporary mapset
A single command can be executed, e.g., to examine properties of a location (here using
the NC SPM sample location):
grass --tmp-mapset /path/to/grassdata/nc_spm_08/ --exec g.proj -p
Computation in a Python script can be executed in the same way:
grass --tmp-mapset /path/to/grassdata/nc_spm_08/ --exec processing.py
Additional parameters are just passed to the script, so we can run the script with
different sets of parameters (here 5, 8 and 3, 9) in different temporary mapsets which is
good for parallel processing.
grass --tmp-mapset /path/to/grassdata/nc_spm_08/ --exec processing.py 5 8
grass --tmp-mapset /path/to/grassdata/nc_spm_08/ --exec processing.py 3 9
The same applies to Bash scripts (and other scripts supported on you platform):
grass --tmp-mapset /path/to/grassdata/nc_spm_08/ --exec processing.sh 5 8
The temporary mapset is automatically deleted after computation, so the script is expected
to export, link or otherwise preserve the output data before ending.
Troubleshooting
Importantly, to avoid an "[Errno 8] Exec format error" there must be a shebang line at the
top of the script (like #!/bin/sh, #!/bin/bash, or #!/usr/bin/env python3) indicating
which interpreter to be used for the script. The script file must have its executable bit
set.
CAVEAT
If you start GRASS using the wxGUI interface you must have a python command in your $PATH
variable. That is, the command must be named python and not something like python3.6.
Rarely some Python installations do not create a python command. In these cases you can
override python by GRASS_PYTHON environmental variable.
Furthermore, if you have more than one version of Python installed, make sure that the
version you want to use with GRASS is set by GRASS_PYTHON environmental variable.
SEE ALSO
List of GRASS environment variables
GRASS GIS Web site
GRASS GIS User Wiki
GRASS GIS Bug Tracker
GRASS GIS 8 Programmer’s Manual
AUTHORS (of this page)
Justin Hickey
Markus Neteler
Hamish Bowman
Martin Landa, Czech Technical University in Prague, Czech Republic
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© 2003-2023 GRASS Development Team, GRASS GIS 8.3.0 Reference Manual