## 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:

- PNG driver
- PS driver (PostScript)
- HTMLMAP driver
- variables for direct rendering
- variables for internal use

Any setting which needs to be modifiable by a GRASS program (e.g. MONITOR) has to be a GRASS gisenv variable.

## GRASS-related Files

GRASS maintains some settings in a number of files on the system. They are detailed below.

## Setting environment variables

Setting environment variables depends on the shell being used:
Bash:

    export VARIABLE=value

Csh:

    setenv VARIABLE value

Cmd.exe (Windows):

    set VARIABLE=value

## Setting environment variables permanently

- To get personal BASH shell definitions (aliases, color listing option, ...) into GRASS, store them in:
  `$HOME/.grass.bashrc`
- To get personal CSH shell definitions (aliases, color listing option, ...) into GRASS, store them in:
  `$HOME/.grass.cshrc`

## Setting GRASS variables

Use g.gisenv within GRASS. This permanently predefines GRASS variables in the `.grassrc6` file.
Usage:

    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 GRASS_GUI
    text

## List of selected (GRASS related) environment variables

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

GISBASE
  directory where GRASS lives. This is set automatically by the startup script.
GISRC
  name of `.grassrc6` file. Defines the system wide value while in a GRASS session.
GRASS_ADDON_PATH
  [grass startup script]
  allows to specify additional paths to local GRASS modules extra to standard distribution.
GRASS_ADDON_ETC
  [libgis, g.findetc]
  specify paths where support files (etc/) may be found external to standard distribution.
GRASS_BATCH_JOB
  defines the name (path) of a shell script to be processed as batch job.
GIS_ERROR_LOG
  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.
GRASS_ERROR_MAIL
  set to any value to send user mail on an error or warning that happens while stderr is being redirected.
GRASS_GNUPLOT
  [i.spectral]
  program to use for plotting gnuplot data.
GRASS_GUI
  either `text` or `gui` to define non-/graphical startup.
  Can also specify the name of the GUI to use, e.g. `tcltk` (gis.m), `oldtcltk` (d.m) or `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 used.
GRASS_FONT_CAP
  [g.mkfontcap, d.font, display drivers]
  specifies an alternative location (to $GISBASE/etc/fontcap) for the font configuration file.
GRASS_HEIGHT
  [d.mon]
  defines the height of GRASS monitor, see also GRASS_WIDTH.
GRASS_HTML_BROWSER
  [init.sh, d.m, gis.m]
  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. com.apple.Safari. 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: /Applications/Safari.app):
  `grep -A 1 "CFBundleIdentifier"` /path/to/application.app`/Contents/Info.plist`
  The signature is the <string> following the <key>, without the bracketing <string> tags.
G_INFO_FORMAT_STANDARD
  [init.sh, wxgui]
  sets percentage output and message formatting style to standard formatting.
G_INFO_FORMAT_GUI
  [init.sh, wxgui]
  sets percentage output and message formatting style to GUI formatting.
G_INFO_FORMAT_SILENT
  [init.sh, wxgui]
  disables percentage output and error messages.
G_INFO_FORMAT_PLAIN
  [init.sh, wxgui]
  sets percentage output and message formatting style to ASCII output without rewinding control characters.
GRASS_INT_ZLIB
  [libgis]
  if the environment variable GRASS_INT_ZLIB exists, new compressed integer (CELL type) raster maps will be compressed using zlib instead of RLE compression. 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.
GRASS_MESSAGE_FORMAT
  [various modules, wxGUI]
  maybe set to either
  - `standard` - sets percentage output and message formatting style to standard formatting,
  - `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.
GRASS_MOUSE_BUTTON
  [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`).
GRASS_PAGER
  [various modules]
  maybe set to either `less` or `more`.
GRASS_PERL
  [used during install process for generating man pages]
  set Perl with path.
GRASS_RND_SEED
  set random seed for r.mapcalc rand() function.
GRASS_SH
  [shell scripts on Windows]
  path to bourne shell interpreter used to run shell scripts.
GRASS_PYTHON
  [wxGUI, Python SWIG]
  set to override Python executable.
  On Mac OS X this should be the pythonw executable for the wxGUI to work.
GRASS_WXBUNDLED
  [wxGUI]
  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.
GRASS_TCLSH
  [nviz]
  set tclsh shell name to override 'tclsh'.
GRASS_XTERM
  [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 Terminal.app.
GRASS_UI_TERM
  set to any value to use the terminal based parser.
GRASS_VERSION
  reports the current version number (used by R-stats interface etc); should not be changed by user.
GRASS_WIDTH
  [d.mon]
  defines the width of GRASS monitor, see also GRASS_HEIGHT.
GRASS_WISH
  [d.m, nviz]
  set wish shell name to override 'wish'.
GRASS_NO_GLX_PBUFFERS
  [nviz]
  set to any value to disable the use of GLX Pbuffers.
GRASS_NO_GLX_PIXMAPS
  [nviz]
  Set to any value to disable the use of GLX Pixmaps.

### List of selected GRASS PNG driver environment variables

> [ These variables control the function of the PNG driver ]

See PNG driver manual page for detailed list of the variables.

### List of selected GRASS PS driver environment variables

> [ These variables control the function of the PS driver ]

See PS driver manual page for detailed list of the variables.

### List of selected HTMLMAP driver environment variables

> [ These variables control the function of the HTMLMAP driver ]

See HTMLMAP driver manual page for detailed list of the variables.

### List of selected GRASS environment variables for direct rendering

> [ In addition to those which are understood by the PNG driver, the following variables affect direct rendering. ]

GRASS_RENDER_IMMEDIATE
  tells the raster library to use its built-in PNG/PS driver rather than connecting to an external monitor process using sockets. If GRASS_RENDER_IMMEDIATE=TRUE is set, there is no need to run `d.mon start=PNG`.
GRASS_FONT
  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.
GRASS_ENCODING
  the encoding to be assumed for text which is drawn using a freetype font; may be any encoding know to iconv.

### 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. ]

GRASS_OVERWRITE
  [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_VERBOSE
  [all modules]
  toggles verbosity level
  - 0 - only errors and warnings are printed
  - 1 - progress 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.
GRASS_REGION
  [libgis]
  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.
WIND_OVERRIDE
  [libgis]
  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 gis.m 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 ]

DEBUG
  [entire GRASS]
  sets level of debug message output (0: no debug messages)

      g.gisenv set=DEBUG=0

WX_DEBUG
  [wxGUI]
  sets level of debug message output for wxGUI (0: no debug messages, 1-5 debug levels)
DM_FORM_MODE
  [d.m]
  sets default form mode (`txt` or `gui`)
GISDBASE
  initial database
GIS_LOCK
  lock ID to prevent parallel GRASS use, process id of the start-up shell script
GRASS_DB_ENCODING
  [d.what.vect/forms library]
  encoding of query form (utf-8, ascii, iso8859-1, koi8-r)
GRASS_GUI
  either `text` or `gui` to define non-/graphical startup.
  Can also specify the name of the GUI to use, e.g. `tcltk` (gis.m), `oldtcltk` (d.m) or `wxpython` (wxGUI). Also exists as a shell environment variable. 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 used.
LOCATION
  full path to location directory
LOCATION_NAME
  initial location name
MAPSET
  initial mapset
OVERWRITE
  [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

$HOME/.grassrc6
  stores the GRASS variables (but not environment variables)
$HOME/.grasslogin6
  stores the DBMI passwords in this hidden file. Only the file owner can access this file.
$HOME/GIS_ERROR_LOG
  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.

### SEE ALSO

Display drivers g.gisenv, g.parser

Last changed: $Date: 2011-12-12 16:25:22 +0100 (Mon, 12 Dec 2011) $

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