If you find this document usefull, please consider ordering a printed hardcopy!

6 GRASS variables

During a GRASS-session some variables are set. The can be printed and modified with the module g.gisenv.
If the module is called without parameters, GRASS displays the current environment variable settings:

g.gisenv
GISDBASE=/home/holl/grassdata
GRASS_DB_ENCODING=utf-8
MAPSET=PERMANENT
LOCATION_NAME=spearfish
GRASS_GUI=tcltk

To display the current mapset, the module needs to be called with the parameter 'MAPSET': g.gisenv MAPSET

To modify a variable, use the following syntax:
g.gisenv set='OVERWRITE=1'

This will set the variable OVERWRITE to overwrite-mode, which is deactivated by default.

A detailed list of GRASS-specific variables can be found at the help-pages:
g.manual variables

Note: Besides the currently mentioned variable 'OVERWRITE' it is also possible to force the vector- and rastermodules to overwrite maps by using the switches -o or -overwrite (with two minus-signs). So it it possible to force overwriting during each command individually, but default maps are still write protected.