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="#enviro">shell environment</a> variables,</li>
<li><a href="#gisenv">GRASS gisenv</a> variables.</li>
</ul>

There are a number of <i>shell</i> environment variable groups:
<ul>
<li><a href="#rendering">variables for rendering</a></li>
<li><a href="#internal">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>$HOME/.grass.bashrc</tt></li>
<li>
To get personal CSH shell definitions (aliases, color listing option, ...)
into GRASS, store them in:<br>
<tt>$HOME/.grass.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>

<a name="enviro"></a>
<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]<br> allows to specify additional paths to
    local GRASS modules or user scripts extra to standard GRASS
    distribution.</dd>

  <dt>GRASS_ADDON_BASE</dt>
  <dd>[grass startup script]<br> allows to specify 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>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_GNUPLOT</dt>
  <dd>[<!-- m.svfit, s.probplt, s.sv -->i.spectral]<br>
    program to use for plotting <em>gnuplot</em> data.</dd>
  
  <dt>GRASS_GUI</dt>
  <dd>either <tt>text</tt> or <tt>gui</tt> to define non-/graphical startup.
    <br><br> 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>[libgis]<br> if the environment variable GRASS_INT_ZLIB exists,
    new compressed <i>integer</i> (CELL type) raster maps will be compressed
    using zlib instead of RLE compression. 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_MESSAGE_FORMAT</dt>
  <dd>[various modules, wxGUI]<br> maybe 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>
    maybe set to either <tt>less</tt> or <tt>more</tt>.</dd>
  
  <dt>GRASS_PERL</dt>
  <dd>[used during install process for generating man pages]<br>
    set Perl with path.</dd>
  
  <dt>GRASS_RND_SEED</dt>
  <dd>set random seed
    for <em><a href="r.mapcalc.html">r.mapcalc</a></em> rand()
    function.</dd>
  
  <!-- HB Sept 2005: I don't think this exists anymore:
       <p>GRASS_STDERR
	 <br>&nbsp; set to any value to prevent user mail on error
	 -->
  <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 pythonw 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_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_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>
</dl>

<a name="rendering"></a>
<h3>List of selected GRASS environment variables for rendering</h3>
<blockquote>
[ In addition to those which are understood by specific <em>GRASS display
 drivers</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>
  or <em><a href="htmldriver.html">html</a></em></dd>
  
  <dt>GRASS_WIDTH</dt>
  <dd>defines the width of output image (default is 640).</dd>
  
  <dt>GRASS_HEIGHT</dt>
  <dd>defines the height of output image (default is 480).</dd>
  
  <dt>GRASS_FRAME</dt>
  <dd>contains 4 coordinates, <em>top,bottom,left,right</em>, defining the initial frame.</dd>

  <dt>GRASS_LINE_WIDTH</dt>
  <dd>defines default line width.</dd>
  
  <dt>GRASS_TEXT_SIZE</dt>
  <dd>defines default text size.</dd>

</dl>

For specific driver-related variables see:

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

<a name="internal"></a>
<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>0 - only errors and warnings are printed</li>
      <li>1 - progress 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>

<a name="gisenv"></a>
<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>GRASS_DB_ENCODING</dt>
  <dd>[d.what.vect/forms library]<br>
    encoding of query form (utf-8, ascii, iso8859-1, koi8-r)</dd>
  
  <dt>GUI</dt>
  <dd>either <tt>text</tt> or <tt>gui</tt> to define non-/graphical startup.
    <br><br> 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 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.</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/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>

<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>