Geografic-Information-System/lib/init/variables.html

<!-- meta page description: GRASS variables and environment variables -->
There are two types of variables:
<ul>
<li><a href="#setting-shell-environment-variables">shell
environment</a> variables,</li>
<li><a href="#setting-grass-gisenv-variables">GRASS gisenv</a>
variables.</li>
</ul>

There are a number of <i>shell</i> environment variable groups:
<ul>
<li><a href="#list-of-selected-grass-environment-variables-for-rendering">variables
for rendering</a></li>
<li><a href="#list-of-selected-internal-grass-environment-variables">variables
for internal use</a></li>
</ul>

<i>Note:</i> Any setting which needs to be modifiable by a GRASS module
(e.g. MONITOR by <em><a href="d.mon.html">d.mon</a></em>) has to be a GRASS
gisenv variable.

<h2>Setting shell environment variables</h2>

Setting shell environment variables depends on the shell being used:
<br><br>
Bash:
<div class="code"><pre>
export VARIABLE=value
</pre></div>
Csh:
<div class="code"><pre>
setenv VARIABLE value
</pre></div>
Cmd.exe (Windows):
<div class="code"><pre>
set VARIABLE=value
</pre></div>

To set up shell environment variables permanently:

<ul>
<li>
To get personal BASH shell definitions (aliases, color listing option, ...)
into GRASS, store them in:<br>
<tt>$HOME/.grass7/bashrc</tt></li>
<li>
To get personal CSH shell definitions (aliases, color listing option, ...)
into GRASS, store them in:<br>
<tt>$HOME/.grass7/cshrc</tt></li>
</ul>


<h2>Setting GRASS gisenv variables</h2>

Use <em><a href="g.gisenv.html">g.gisenv</a></em> within GRASS. This permanently
predefines GRASS variables in the <tt>.grass7/rc</tt> file.
<br><br>
Usage:
<div class="code"><pre>
g.gisenv set="VARIABLE=VALUE"
</pre></div>

It looks unusual with two equals signs, but <em>g.gisenv</em> serves dual duty for
getting and setting GRASS variables.
<p>If the user just specifies a variable name, it defaults to <b>get</b> mode.
For example:
<div class="code"><pre>
g.gisenv MAPSET
PERMANENT
</pre></div>

<h2>List of selected (GRASS related) shell environment variables</h2>

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

<dl>
  
  <dt>GISBASE</dt>
  <dd>directory where GRASS lives. This is set automatically by the
    startup script.</dd>
  
  <dt>GISRC</dt>
  <dd>name of <tt>.grass7/rc</tt> file. Defines the system wide value
    while in a GRASS session.</dd>
  
  <dt>GRASS_ADDON_PATH</dt>
  <dd>[grass startup script, g.extension]<br>
    specifies additional path(s) containing local and/or custom GRASS 
    modules extra to the standard distribution.</dd>

  <dt>GRASS_ADDON_BASE</dt>
  <dd>[grass startup script]<br> allows specifying additional GISBASE
    for local GRASS modules (normally installed as GRASS Addons
    by <tt>g.extension</tt> module) extra to standard
    distribution. The default on GNU/Linux
    is <tt>$HOME/.grass7/addons</tt>, on MS
    Windows <tt>$APPDATA\GRASS7\addons</tt>.</dd>
  
  <dt>GRASS_ADDON_ETC</dt>
  <dd>[libgis, g.findetc]<br>
    specify paths where support files (etc/) may be found external to
    standard distribution.</dd>
  
  <dt>GRASS_BATCH_JOB</dt>
  <dd>defines the name (path) of a shell script to be processed as
  batch job.</dd>

  <dt>GRASS_COMPRESSOR</dt>
  <dd>[libraster]<br>
    the compression method for new raster maps can be set with the
    environment variable GRASS_COMPRESSOR. Supported methods are RLE, 
    ZLIB, LZ4, and BZIP2 if GRASS has been compiled with BZIP2 support. 
    The default is ZLIB which can be changed with e.g. 
    <tt>GRASS_COMPRESSOR=LZ4</tt></dd>

  <dt>GRASS_DB_ENCODING</dt>
  <dd>[various modules, wxGUI]<br>
    encoding for vector attribute data (utf-8, ascii, iso8859-1, koi8-r)</dd>
  
  <dt>GIS_ERROR_LOG</dt>
  <dd>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, <tt>$HOME/GIS_ERROR_LOG</tt> is used instead. The file will
   only be used if it already exists.</dd>

  <dt>GRASS_ERROR_MAIL</dt>
  <dd>set to any value to send user mail on an error or warning that 
    happens while stderr is being redirected.</dd>
  
  <dt>GRASS_FONT</dt>
  <dd>[display drivers]<br>
    specifies the font as either the name of a font from
    <tt>$GISBASE/etc/fontcap</tt> (or alternative fontcap file
    specified by GRASS_FONT_CAP), or alternatively the full path to a
    FreeType font file.</dd>
  
  <dt>GRASS_ENCODING</dt>
  <dd>[display drivers]<br>
    the encoding to be assumed for text which is drawn using a
    freetype font; may be any encoding know to <em>iconv</em>.</dd>

  <dt>GRASS_FONT_CAP</dt>
  <dd>[g.mkfontcap, d.font, display drivers]<br>
    specifies an alternative location (to <tt>$GISBASE/etc/fontcap</tt>) for 
    the font configuration file.</dd>
  
  <dt>GRASS_FULL_OPTION_NAMES</dt>
  <dd>[parser]<br>
    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.</dd>
  
  <dt>GRASS_GUI</dt>
  <dd>either <tt>text</tt> (text user interface), <tt>gtext</tt> (text
  user interface with GUI welcome screen), or <tt>gui</tt> (graphical
  user interface) to define non-/graphical startup. Can also specify
  the name of the GUI to use, e.g. <tt>wxpython</tt>
  (<em><a href="wxGUI.html">wxGUI</a></em>). 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.</dd>
    
  <dt>GRASS_HTML_BROWSER</dt>
  <dd>[init.sh, wxgui]<br> defines name of HTML browser. For most
    platforms this should be an executable in your PATH, or the full
    path to an executable.<br>  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):<br> &nbsp; &nbsp; <code>grep -A 1
    &quot;CFBundleIdentifier&quot;</code> <i>/path/to/application.app</i><code>/Contents/Info.plist</code><br>
    &nbsp; The signature is the &lt;string&gt; following the
    &lt;key&gt;, without the bracketing &lt;string&gt; tags.</dd>

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

  <dt>GRASS_ZLIB_LEVEL</dt>
  <dd>[libgis]<br> 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, DCELL).
    <br><br>
    Valid zlib compression levels are -1 to 9. The <tt>GRASS_ZLIB_LEVEL=-1</tt> corresponds
    to the zlib default value (equivalent to <tt>GRASS_ZLIB_LEVEL=6</tt>). Often
    <tt>GRASS_ZLIB_LEVEL=1</tt> gives the best compromise between speed and compression.
    <br><br>
    If the variable doesn't exist, or the value cannot be parsed as an
    integer, zlib's default compression level 6 will be used.</dd>
  
  <dt>GRASS_MESSAGE_FORMAT</dt>
  <dd>[various modules, wxGUI]<br>
    it may be set to either
    <ul>
      <li><tt>standard</tt> - sets percentage output and message
	formatting style to standard formatting,</li>
      <li><tt>gui</tt> - sets percentage output and message formatting
	style to GUI formatting,</li>
      <li><tt>silent</tt> - disables percentage output and error
	messages,</li>
      <li><tt>plain</tt> - sets percentage output and message
	formatting style to ASCII output without rewinding control
	characters.</li>
  </ul></dd>
  
  <dt>GRASS_MOUSE_BUTTON</dt>
  <dd>[various modules]<br> 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 <tt>132</tt> will swap middle and right
    buttons. Note that this variable should be set before a display
    driver is initialized (e.g.,
    <tt>d.mon x0</tt>).</dd>
  
  <dt>GRASS_PAGER</dt>
  <dd>[various modules]<br>
    it may be set to either <tt>less</tt>, <tt>more</tt>, or <tt>cat</tt>.</dd>
  
  <dt>GRASS_PERL</dt>
  <dd>[used during install process for generating man pages]<br>
    set Perl with path.</dd>
  
  <dt>GRASS_SKIP_MAPSET_OWNER_CHECK</dt>
  <dd>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.</dd>

  <dt>GRASS_SH</dt>
  <dd>[shell scripts on Windows]<br>
    path to bourne shell interpreter used to run shell scripts.</dd>

  <dt>GRASS_SIGSEGV_ON_ERROR</dt>
  <dd>Raise SIGSEGV if an error occures]<br>
  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.</dd>

  <dt>GRASS_PYTHON</dt>
  <dd>[wxGUI, Python Ctypes]<br>
    set to override Python executable.<br>
    On Mac OS X this should be the <tt>pythonw</tt> executable for the
    wxGUI to work.</dd>
  
  <dt>GRASS_VECTOR_LOWMEM</dt>
  <dd>[vectorlib]<br>
    If the environment variable GRASS_VECTOR_LOWMEM exists, memory
    consumption will be reduced when building vector topology
    support structures. Recommended for creating large vectors.</dd>

  <dt>GRASS_VECTOR_OGR</dt>
  <dd>[vectorlib, v.external.out]<br> If the environment variable
    GRASS_VECTOR_OGR exists and vector output format defined
    by <em><a href="v.external.out.html">v.external.out</a></em> is
    PostgreSQL, vector data is written by OGR data provider even
    the native PostGIS data provider is available.</dd>

  <dt>GRASS_VECTOR_EXTERNAL_IMMEDIATE</dt>
  <dd>[vectorlib, v.external.out]<br> If the environment variable
    GRASS_VECTOR_EXTERNAL_IMMEDIATE exists and vector output format
    defined
    by <em><a href="v.external.out.html">v.external.out</a></em> 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).</dd>

  <dt>GRASS_VECTOR_EXTERNAL_IGNORE</dt>
  <dd>[vectorlib]<br> If the environment variable
    GRASS_VECTOR_EXTERNAL_IGNORE exists, output vector format defined
    by <em><a href="v.external.out.html">v.external.out</a></em> is
    ignored. The format is always native.</dd>

  <dt>GRASS_VECTOR_TEMPORARY</dt>
  <dd>[vectorlib]<br> 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:
    <ul>
      <li><tt>keep</tt> - the temporary vector map is not deleted when
      closing the map.
      <li><tt>move</tt> - the temporary vector map is moved to the
      current mapset when closing the map.</li>
      <li><tt>delete</tt> - the temporary vector map is deleted when
      closing the map.
      </li>
    </ul>    
    Default value is <tt>keep</tt>.

    Note that temporary vector maps are not visible to the user
    via <em><a href="g.list.html">g.list</a></em>
    or <em><a href="wxGUI.html">wxGUI</a></em>. They are used
    internally by the GRASS modules and deleted automatically when
    GRASS session is quited.</dd>

  <dt>GRASS_VECTOR_TMPDIR_MAPSET</dt>
  <dd>[vectorlib]<br> By default GRASS temporary directory is located in
  <tt>$LOCATION/$MAPSET/.tmp/$HOSTNAME</tt>. 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).<br>
  Important note: This variable is currently used only in vector
  library. In other words the variable is ignored by raster or
  raster3d library.</dd>

  <dt>GRASS_VECTOR_TOPO_DEBUG</dt>
  <dd>[vectorlib, v.generalize]<br> If the environment variable
  GRASS_VECTOR_TOPO_DEBUG
  exists, <em><a href="v.generalize.html">v.generalize</a></em> runs
  in extremely slow debug mode.</dd>

  <dt>GRASS_WXBUNDLED</dt>
  <dd>[wxGUI]<br>
    set to tell wxGUI that a bundled wxPython will be used.<br>
    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.</dd>

  <dt>GRASS_WXVERSION</dt>
  <dd>[wxGUI]<br>
    set to tell wxGUI which version of wxPython to use.<br>
    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.</dd>

  <dt>GRASS_XTERM</dt>
  <dd>[lib/init/grass-xterm-wrapper, lib/init/grass-xterm-mac]<br>
    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.</dd>
  
  <dt>GRASS_UI_TERM</dt>
  <dd>set to any value to use the terminal based parser.</dd>

  <dt>GRASS_VERSION</dt>
  <dd>reports the current version number (used by R-stats interface etc);
    should not be changed by user.</dd>
    
  <dt>GRASS_NO_GLX_PBUFFERS</dt>
  <dd>[nviz]<br>
    set to any value to disable the use of GLX Pbuffers.</dd>
  
  <dt>GRASS_NO_GLX_PIXMAPS</dt>
  <dd>[nviz]<br>
    Set to any value to disable the use of GLX Pixmaps.</dd>

  <dt>OMP_NUM_THREADS</dt>
  <dd>[OpenMP]<br>
    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 processing.</dd>

  <dt>TMPDIR, TEMP, TMP</dt>
  <dd>[Various GRASS GIS commands and wxGUI]<br>
  <!-- what about Windows %TEMP% and http://trac.osgeo.org/grass/ticket/560#comment:21 ? -->
	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.</dd>
</dl>

<h3>List of selected GRASS environment variables for rendering</h3>
<blockquote>
[ In addition to those which are understood by
 specific <em><a href="displaydrivers.html">GRASS display
 drivers</a></em>, the following variables affect rendering. ]
</blockquote>

<dl>
  <dt>GRASS_RENDER_IMMEDIATE</dt>
  <dd>tells the display library which driver to use; possible
  values: <em><a href="cairodriver.html">cairo</a></em>, <em><a href="pngdriver.html">png</a></em>, <em><a href="psdriver.html">ps</a></em>,
    <em><a href="htmldriver.html">html</a></em>
    or <em>default</em><br>Default display driver
    is <em><a href="cairodriver.html">cairo</a></em> (if available)
    otherwise <em><a href="pngdriver.html">png</a></em>.
  </dd>
  
  <dt>GRASS_RENDER_WIDTH</dt>
  <dd>defines the width of output image (default is 640).</dd>
  
  <dt>GRASS_RENDER_HEIGHT</dt>
  <dd>defines the height of output image (default is 480).</dd>
  
  <dt>GRASS_RENDER_FILE</dt>
  <dd>the name of the resulting image file.</dd>

  <dt>GRASS_RENDER_FRAME</dt>
  <dd>contains 4 coordinates, <em>top,bottom,left,right</em> (pixel
  values) with respect to the top left corner of the output image,
  defining the initial frame.</dd>

  <dt>GRASS_RENDER_LINE_WIDTH</dt>
  <dd>defines default line width.</dd>
  
  <dt>GRASS_RENDER_TEXT_SIZE</dt>
  <dd>defines default text size.</dd>

  <dt>GRASS_RENDER_COMMAND</dt>
  <dd>external command called by display library to render data (see
    example in <em><a href="displaydrivers.html">display
    drivers</a></em> page for details).<br>Currently only Python scripts
    are supported.</dd>

</dl>

For specific driver-related variables see:

<ul>
  <li><em><a href="cairodriver.html">Cairo display driver</a></em></li>
  <li><em><a href="pngdriver.html">PNG display driver</a></em></li>
  <li><em><a href="psdriver.html">PS (Postscript) display driver</a></em></li>
  <li><em><a href="htmldriver.html">HTML display driver</a></em></li>
</ul>

<h3>List of selected internal GRASS environment variables</h3>
<blockquote>
  [ These variables are intended <b>for internal use only</b> 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. ]
</blockquote>

<dl>
  <dt>GRASS_OVERWRITE</dt>
  <dd>[all modules]<br>
    toggles map overwrite.
    <ul>
      <li>0 - maps are protected (default),</li>
      <li>1 - maps with identical names will be overwritten.</li>
    </ul>
    This variable is automatically created
    by <em><a href="g.parser.html">g.parser</a></em> so that the
    <tt>--overwrite</tt> 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.</dd>
  
  <dt>GRASS_VERBOSE</dt>
  <dd>[all modules]<br>
    toggles verbosity level
    <ul>
      <li>-1 - complete silence (also errors and warnings are discarded)</li>
      <li>0 - only errors and warnings are printed</li>
      <li>1 - progress and important messages are printed (percent complete)</li>
      <li>2 - all module messages are printed</li>
      <li>3 - additional verbose messages are printed</li>
    </ul>
    This variable is automatically created by <em><a href="g.parser.html">g.parser</a></em>
    so that the <tt>--verbose</tt> or <tt>--quiet</tt> flags will be inherited
    by dependent modules as the script runs.</dd>
  
  <dt>GRASS_REGION</dt>
  <dd>[libgis]<br>
    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.</dd>
  
  <dt>WIND_OVERRIDE</dt>
  <dd>[libgis]<br>
    it causes programs to use the specified named region (created with
    e.g. <tt>g.region save=...</tt>) to be used as the current region, instead of
    the region from the WIND file.<br><br>
    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.</dd>
</dl>

<h2>List of selected GRASS gisenv variables</h2>

<blockquote>
  [ Use <em><a href="g.gisenv.html">g.gisenv</a></em> to get/set/unset/change them ]
</blockquote>

<dl>
  
  <dt>DEBUG</dt>
  <dd>[entire GRASS]<br>
    sets level of debug message output (0: no debug messages)
<div class="code"><pre>
g.gisenv set=DEBUG=0
</pre></div>

  <dt>WX_DEBUG</dt>
  <dd>[wxGUI]<br>
    sets level of debug message output for <em><a href="wxGUI.html">wxGUI</a></em> (0: no debug messages, 1-5 debug levels)
  
  <dt>GISDBASE</dt>
  <dd>initial database</dd>

  <dt>GIS_LOCK</dt>
  <dd>lock ID to prevent parallel GRASS use,
    <br>process id of the start-up shell script</dd>
  
  <dt>GUI</dt>
  <dd>See <tt>GRASS_GUI</tt> environmental variable for details.</dd>
  
  <dt>LOCATION</dt>
  <dd>full path to location directory</dd>
  
  <dt>LOCATION_NAME</dt>
  <dd>initial location name</dd>
  
  <dt>MAPSET</dt>
  <dd>initial mapset</dd>
  
  <dt>OVERWRITE</dt>
  <dd>[all modules]<br>
    toggles map overwrite.
    <ul>
      <li>0 - maps are protected (default),</li>
      <li>1 - maps with identical names will be overwritten.</li>
    </ul>
    This variable is automatically created
    by <em><a href="g.parser.html">g.parser</a></em> so that the
    <tt>--overwrite</tt> 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.</dd>
</dl>

<h2>GRASS-related Files</h2>

<dl>
  <dt><tt>$HOME/.grass7/rc</tt></dt>
  <dd>stores the GRASS gisenv variables (not shell environment variables)</dd>

  <dt><tt>$HOME/.grass7/bashrc</tt></dt>
  <dd>stores the shell environment variables (Bash only)</dd>

  <dt><tt>$HOME/.grass7/env.bat</tt></dt>
  <dd>stores the shell environment variables (MS Windows only)</dd>
  
  <dt><tt>$HOME/.grass7/login</tt></dt>
  <dd>stores the DBMI passwords in this hidden file.
    Only the file owner can access this file.</dd>

  <dt><tt>$HOME/GIS_ERROR_LOG</tt></dt>
  <dd>if this file exists then all GRASS error and warning messages are 
    logged here. Applies to current user. To generate the file, use:
    <tt>touch $HOME/GIS_ERROR_LOG</tt><br>
   See also GIS_ERROR_LOG variable.</dd>
</dl>

Note: On MS Windows the files are stored in <tt>%APPDATA%</tt>.

<h2>SEE ALSO</h2>

<em>
  <a href="g.gisenv.html">g.gisenv</a>,
  <a href="g.parser.html">g.parser</a>
</em>

<p>
<i>Last changed: $Date$</i>