Ubuntu Manpage: SYNOPSIS

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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
       import grass.script.setup as gsetup
       gs.message(’Current GRASS GIS 8 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.

AUTHORS (of this page)

       Justin Hickey
       Markus Neteler
       Hamish Bowman
       Martin Landa, Czech Technical University in Prague, Czech Republic

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       © 2003-2022 GRASS Development Team, GRASS GIS 8.2.0 Reference Manual