# GRASS Help System

## GRASS DATABASE DIRECTORY STRUCTURE

The files that GRASS uses and creates are stored in a special place on your system. Exactly where GRASS programs and data are stored on your system will depend on where you install GRASS. However, wherever GRASS is installed on your system, it will use a pre-defined directory structure. To view a diagram of the GRASS directory structure, select directory tree.

All users' GRASS data are stored under a directory which is also known by the variable name $GISDBASE. The $GISDBASE variable stands for "GIS Data Base directory". For example, at your site, the $GISDBASE directory might be /usr/grass4/data.

Beneath this directory, there are subdirectories which are created when the user enters GRASS. Each subdirectory of the $GISBASE directory is termed a GRASS "location", and is known by the variable $LOCATION_NAME. Typically, each of these location directories will store data for a different geographic location. However, this is up to the user.

Beneath each location subdirectory, there will be further subdirectories called "mapset" subdirectories. Each "mapset" contains a set of maps. All of the mapset directories stored beneath a given location should contain data relevant to the same general geographic region. All of the mapsets stored under the same location directory MUST use the same map coordinate system and map projection.

In addition to each user's individual mapset, each location directory must contain a special mapset directory named "PERMANENT". This directory contains default information for all of the mapsets under a given location. It is made automatically by GRASS whenever the user establishes a new location.

Under each mapset directory, GRASS data directories are stored. These directories are created by GRASS as they become needed. There will also be some files under each mapset directory. The major data directories and files found under a GRASS mapset directory are listed below:

Vector Data Directories
Raster Data Directories
Site Data Directories
Mapset files

For more information on a specific directory, select a directory and press ESC.

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Automatically created on: Sun Mar 5 12:05:42 2006