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GRASS variables and environment variables

       There are two types of variables:

           ·   shell environment variables,

           ·   GRASS gisenv variables.
       There are a number of shell environment variable groups:

           ·   variables for rendering

           ·   variables for internal use
       Note:  Any  setting which needs to be modifiable by a GRASS module (e.g. MONITOR by d.mon)
       has to be a GRASS gisenv variable.

Setting shell environment variables

       Setting shell environment variables depends on the shell being used:
       export VARIABLE=value
       setenv VARIABLE value
       Cmd.exe (Windows):
       set VARIABLE=value
       To set up shell environment variables permanently:

           ·   To get personal BASH shell definitions (aliases, color listing option, ...)   into
               GRASS, store them in:

           ·   To  get  personal CSH shell definitions (aliases, color listing option, ...)  into
               GRASS, store them in:

Setting GRASS gisenv variables

       Use g.gisenv within GRASS. This permanently predefines GRASS variables in  the  .grass7/rc
       g.gisenv set="VARIABLE=VALUE"
       It  looks  unusual  with  two  equals signs, but g.gisenv serves dual duty for getting and
       setting GRASS variables.

       If the user just specifies a variable name, it defaults to get mode.  For example:
       g.gisenv MAPSET

List of selected (GRASS related) shell environment variables

       [ To be set from the terminal shell or startup scripts ]

           directory where GRASS lives. This is set automatically by the startup script.

           name of .grass7/rc file. Defines the system wide value while in a GRASS session.

           [grass startup script, g.extension]
           specifies additional path(s) containing local and/or custom GRASS modules extra to the
           standard distribution.

           [grass startup script]
           allows  specifying  additional  GISBASE for local GRASS modules (normally installed as
           GRASS Addons by g.extension module) extra to standard  distribution.  The  default  on
           GNU/Linux is $HOME/.grass7/addons, on MS Windows $APPDATA\GRASS7\addons.

           [libgis, g.findetc]
           specify   paths  where  support  files  (etc/)  may  be  found  external  to  standard

           defines the name (path) of a shell script to be processed as batch job.

           the compression method for new raster maps can be set with  the  environment  variable
           GRASS_COMPRESSOR.  Supported  methods are RLE, ZLIB, LZ4, BZIP2, and ZSTD. The default
           is ZLIB which can be changed with e.g. GRASS_COMPRESSOR=ZSTD

           [various modules, wxGUI]
           encoding for vector attribute data (utf-8, ascii, iso8859-1, koi8-r)

           If set, GIS_ERROR_LOG should be the absolute path to the log  file  (a  relative  path
           will  be  interpreted  relative to the process’ cwd, not the cwd at the point the user
           set the variable). If not set, $HOME/GIS_ERROR_LOG is used instead. The file will only
           be used if it already exists.

           set to any value to send user mail on an error or warning that happens while stderr is
           being redirected.

           [display drivers]
           specifies the font as  either  the  name  of  a  font  from  $GISBASE/etc/fontcap  (or
           alternative  fontcap file specified by GRASS_FONT_CAP), or alternatively the full path
           to a FreeType font file.

           [display drivers]
           the encoding to be assumed for text which is drawn using a freetype font; may  be  any
           encoding know to iconv.

           [g.mkfontcap, d.font, display drivers]
           specifies an alternative location (to $GISBASE/etc/fontcap) for the font configuration

           Generates a warning if GRASS_FULL_OPTION_NAMES is set (to anything) and a found string
           is not an exact match for the given string.

           either  text  (text  user  interface),  gtext  (text  user  interface with GUI welcome
           screen), or gui (graphical user interface) to define non-/graphical startup. Can  also
           specify  the  name  of  the  GUI to use, e.g. wxpython (wxGUI). Also exists as a GRASS
           gisenv variable (see below). If this shell variable exists at GRASS startup,  it  will
           determine  the  GUI  used.  If  it is not defined startup will default to the last GUI

           [, wxgui]
           defines name of HTML browser. For most platforms this should be an executable in  your
           PATH, or the full path to an executable.
           Mac  OS  X  runs applications differently from the CLI.  Therefore, GRASS_HTML_BROWSER
           should be the application’s signature, which is a  domain-like  name,  just  reversed,
           i.e.  To  find  an application’s signature, type the following in a
           Terminal (fill in the path to the application you  are  interested  in,  for  example:
           grep -A 1 "CFBundleIdentifier" /path/to/
           The  signature  is  the  <string> following the <key>, without the bracketing <string>

           if the environment variable GRASS_INT_ZLIB exists and has the value 0, new  compressed
           integer (CELL type) raster maps will be compressed using RLE compression.
           If the variable doesn’t exist, or the value is non-zero, zlib compression will be used
           instead. Such rasters will have a compressed value of 2 in the cellhd file.
           Obviously, decompression is controlled by  the  raster’s  compressed  value,  not  the
           environment variable.

           if  the environment variable GRASS_ZLIB_LEVEL exists and its value can be parsed as an
           integer, it determines the compression level used when new compressed raster maps  are
           compressed  using zlib compression. This applies to all raster map types (CELL, FCELL,
           Valid zlib compression levels are -1 to 9. The GRASS_ZLIB_LEVEL=-1 corresponds to  the
           zlib  default value (equivalent to GRASS_ZLIB_LEVEL=6). Often GRASS_ZLIB_LEVEL=1 gives
           the best compromise between speed and compression.
           If the variable doesn’t exist, or the value cannot be parsed  as  an  integer,  zlib’s
           default compression level 6 will be used.

           [various modules, wxGUI]
           it may be set to either

           ·   standard  -  sets  percentage  output  and  message  formatting  style to standard

           ·   gui - sets percentage output and message formatting style to GUI formatting,

           ·   silent - disables percentage output and error messages,

           ·   plain - sets percentage output  and  message  formatting  style  to  ASCII  output
               without rewinding control characters.

           [various modules]
           swaps  mouse buttons for two-button or left-handed mice. Its value has three digits 1,
           2, and 3, which represent  default  left,  middle,  and  right  buttons  respectively.
           Setting  to  132 will swap middle and right buttons. Note that this variable should be
           set before a display driver is initialized (e.g., d.mon x0).

           [various modules]
           it may be set to either less, more, or cat.

           [used during install process for generating man pages]
           set Perl with path.

           By default it is not possible to work with MAPSETs that are not owned by current user.
           Setting this variable to any non-empty value allows the check to be skipped.

           [shell scripts on Windows]
           path to bourne shell interpreter used to run shell scripts.

           Raise SIGSEGV if an error occurs]
           This  variable  can be set for debugging purpose. The call of G_fatal_error() will end
           in a segmentation violation. GDB can be used to trace the source of the error.

           [wxGUI, Python Ctypes]
           set to override Python executable.
           On Mac OS X this should be the pythonw executable for the wxGUI to work.

           If the environment variable GRASS_VECTOR_LOWMEM exists,  memory  consumption  will  be
           reduced  when  building  vector  topology support structures. Recommended for creating
           large vectors.

           [vectorlib, v.external.out]
           If the environment variable GRASS_VECTOR_OGR exists and vector output  format  defined
           by  v.external.out is PostgreSQL, vector data is written by OGR data provider even the
           native PostGIS data provider is available.

           [vectorlib, v.external.out]
           If the environment variable GRASS_VECTOR_EXTERNAL_IMMEDIATE exists and  vector  output
           format  defined by v.external.out is non-native, vector features are written to output
           external datasource immediately. By default, the vector library writes output data  to
           a  temporary  vector  map  in native format and when closing the map, the features are
           transferred  to  output  external  datasource.  Note:  if  output  vector  format   is
           topological  PostGIS  format,  then  the vector library writes features immediately to
           output database (in this case GRASS_VECTOR_EXTERNAL_IMMEDIATE is ignored).

           If the environment variable GRASS_VECTOR_EXTERNAL_IGNORE exists, output vector  format
           defined by v.external.out is ignored. The format is always native.

           If  the  environment variable GRASS_VECTOR_TEMPORARY exists, GRASS vector library will
           operate on temporary vector maps.  New  vector  maps  will  be  created  in  temporary
           directory (see GRASS_VECTOR_TMPDIR_MAPSET variable), existing vector maps will be read
           (if found) also from this directory. It may be set to either:

           ·   keep - the temporary vector map is not deleted when closing the map.

           ·   move - the temporary vector map is moved to the current mapset  when  closing  the

           ·   delete - the temporary vector map is deleted when closing the map.
       Default  value  is  keep.  Note that temporary vector maps are not visible to the user via
       g.list or wxGUI. They are used internally by the GRASS modules and  deleted  automatically
       when GRASS session is quited.

           By  default  GRASS temporary directory is located in $LOCATION/$MAPSET/.tmp/$HOSTNAME.
           If GRASS_VECTOR_TMPDIR_MAPSET is set to ’0’, the temporary  directory  is  located  in
           TMPDIR  (environmental  variable defined by the user or GRASS initialization script if
           not given).
           Important note: This variable is currently used only in vector library. In other words
           the variable is ignored by raster or raster3d library.

           [vectorlib, v.generalize]
           If  the  environment  variable  GRASS_VECTOR_TOPO_DEBUG  exists,  v.generalize runs in
           extremely slow debug mode.

           set to tell wxGUI that a bundled wxPython will be used.
           When set, the wxGUI  will  not  check  the  wxPython  version,  as  this  function  is
           incompatible  with  a  bundled wxPython.  It is up to the packager to make sure that a
           compatible wxPython version is bundled.

           set to tell wxGUI which version of wxPython to use.
           When set, the wxGUI will select the given wxPython version. It’s useful when  multiple
           versions  of  wxPython  are installed and the user wants to run wxGUI with non-default
           wxPython version.

           [lib/init/grass-xterm-wrapper, lib/init/grass-xterm-mac]
           set  to  any  value  (e.g.  rxvt,  aterm,  gnome-terminal,  konsole)   to   substitute
           ’x-terminal-emulator’  or  ’xterm’.  The  Mac OS X app startup defaults to an internal
           ’$GISBASE/etc/grass-xterm-mac’, which emulates the necessary  xterm  functionality  in

           set to any value to use the terminal based parser.

           reports  the  current  version  number  (used by R-stats interface etc); should not be
           changed by user.

           set to any value to disable the use of GLX Pbuffers.

           Set to any value to disable the use of GLX Pixmaps.

           If OpenMP support is enabled this limits the number of threads.  The default is set to
           the  number  of  CPUs  on  the  system.   Setting to ’1’ effectively disables parallel

           [Various GRASS GIS commands and wxGUI]
           The default wxGUI temporary directory is chosen from a  platform-dependent  list,  but
           the  user  can  control  the selection of this directory by setting one of the TMPDIR,
           TEMP or TMP environment variables Hence the wxGUI uses $TMPDIR  if  it  is  set,  then
           $TEMP, otherwise /tmp.

   List of selected GRASS environment variables for rendering
       [  In  addition  to  those  which  are  understood  by specific GRASS display drivers, the
       following variables affect rendering. ]

           tells the display library which driver to use; possible values: cairo, png,  ps,  html
           or default
           Default display driver is cairo (if available) otherwise png.

           defines the width of output image (default is 640).

           defines the height of output image (default is 480).

           the name of the resulting image file.

           contains  4  coordinates, top,bottom,left,right (pixel values) with respect to the top
           left corner of the output image, defining the initial frame.

           defines default line width.

           defines default text size.

           external command called by display library to render  data  (see  example  in  display
           drivers page for details).
           Currently  only  Python  scripts are supported.  For specific driver-related variables

           ·   Cairo display driver

           ·   PNG display driver

           ·   PS (Postscript) display driver

           ·   HTML display driver

   List of selected internal GRASS environment variables
       [ These variables are intended for internal use only by the GRASS software  to  facilitate
       communication between the GIS engine, GRASS scripts, and the GUI.  The user should not set
       these in a GRASS session. They are meant to be set locally for specific commands. ]

           [all modules]
           toggles map overwrite.

           ·   0 - maps are protected (default),

           ·   1 - maps with identical names will be overwritten.
       This variable is automatically created by g.parser so that the --overwrite option will  be
       inherited  by  dependent  modules  as  the script runs. Setting either the GRASS_OVERWRITE
       environment variable or the OVERWRITE gisenv variable detailed below will cause maps  with
       identical names to be overwritten.

           [all modules]
           toggles verbosity level

           ·   -1 - complete silence (also errors and warnings are discarded)

           ·   0 - only errors and warnings are printed

           ·   1 - progress and important messages are printed (percent complete)

           ·   2 - all module messages are printed

           ·   3 - additional verbose messages are printed
       This  variable is automatically created by g.parser so that the --verbose or --quiet flags
       will be inherited by dependent modules as the script runs.

           override region settings, separate parameters with a ";". Format is the same as in the
           WIND region settings file. Otherwise use is the same as WIND_OVERRIDE.

           it  causes  programs  to  use  the  specified named region (created with e.g. g.region
           save=...) to be used as the current region, instead of the region from the WIND file.
           This allows programs such as the GUI to run external commands on an  alternate  region
           without having to modify the WIND file then change it back afterwards.

List of selected GRASS gisenv variables

       [ Use g.gisenv to get/set/unset/change them ]

           [entire GRASS]
           sets level of debug message output (0: no debug messages)
           g.gisenv set=DEBUG=0

           sets level of debug message output for wxGUI (0: no debug messages, 1-5 debug levels)

           initial database

           lock ID to prevent parallel GRASS use,
           process id of the start-up shell script

           See GRASS_GUI environmental variable for details.

           full path to location directory

           initial location name

           initial mapset

           [all modules]
           toggles map overwrite.

           ·   0 - maps are protected (default),

           ·   1 - maps with identical names will be overwritten.
       This  variable is automatically created by g.parser so that the --overwrite option will be
       inherited by dependent modules as the script  runs.  Setting  either  the  GRASS_OVERWRITE
       environment  variable or the OVERWRITE gisenv variable detailed below will cause maps with
       identical names to be overwritten.

GRASS-related Files

           stores the GRASS gisenv variables (not shell environment variables)

           stores the shell environment variables (Bash only)

           stores the shell environment variables (MS Windows only)

           stores the DBMI passwords in this hidden file.  Only the file owner  can  access  this

           if this file exists then all GRASS error and warning messages are logged here. Applies
           to current user. To generate the file, use: touch $HOME/GIS_ERROR_LOG
           See also GIS_ERROR_LOG variable.   Note:  On  MS  Windows  the  files  are  stored  in


        g.gisenv, g.parser

       Last changed: $Date: 2018-06-07 16:45:42 +0200 (Thu, 07 Jun 2018) $

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