James Madison University
Integrated Science and Technology
Environment Sector
Author: Cate Wardell
Advisor: Dr. Steve Frysinger
Last updated: 26-Apr-2001

IMPORTANT: You may want to print out this page so you can follow along while logging in to the computer in the Lab.

IMPORTANT: Before attempting to log-in be sure you have done the following:

• You have obtained the password for the DELL log-in from the system administrator
• You have obtained a username and password for the Linux log-in from the system administrator
• You have the Linux boot disk

If you have any difficulties while attempting to log-in, contact the system administrator.

• Before turning on the computer, place the Linux boot disk in the 3.5" disk drive.
• Turn on the computer.
• The computer will prompt you for the password for the DELL log-in. Enter the password and press <Enter>.
• The computer will automatically load Red Hat Linux from the hard drive. This may take a few minutes.
• The computer will prompt you for your username for the Linux log-in. Enter your username and press <Enter>.
• The computer will prompt you for your password for the Linux log-in. Enter your password and press <Enter>.

You are now ready to use GRASS!

IMPORTANT: GRASS is not controlled by menu options, but by commands that are typed at the command line interface in a terminal. In this tutorial, commands that should be typed in the command line interface are written in a different text. The literal command will often have options after it. A typical command will be similar to: command -flag parameters

In order to run GRASS you will need to start a terminal for typing commands. To open a new terminal:

• Click on the programs menu button on the task bar.
• Point to the "Utilities" sub-menu
• Click on "Gnome Terminal" in the sub-menu

A screen will appear that is similar to Figure 1.1 below.

Figure 1.1: An open command line interface terminal in Linux

To start the GRASS program:

• Type grass4.3 at the command line and press <Enter>.

A screen will appear that is similar to Figure 1.2 below.

Figure 1.2: Opening GRASS screen

Three fields need to be specified in order to use the GRASS program. To set the fields:

• Press the <Enter> key until the "LOCATION" field is highlighted. Type "tutorial".
• Press the <Enter> key until the "MAPSET" is highlighted. Type "virginia".
• Press the <Enter> key until the "DATABASE" is highlighted. Type "/usr/local/grassdata/"
• Press <Esc><Enter> to continue.
• If you would like to cancel out of opening GRASS, press <Ctrl><C>.

The welcome screen will appear and will be similar to Figure 1.3 below.

Figure 1.3: GRASS welcome message

The prompt in the command line interface will now look similar to:

GRASS:~

All your GRASS commands should be typed at this prompt.

IMPORTANT: After typing a command at the prompt, always press the <Enter> key.

You can view the settings of your current GRASS session. To print out your settings to the command line interface:

• Type g.gisenv

GRASS will print information about the current session to the command line interface. The print out will be similar to Figure 1.4 below.

Figure 1.4: GRASS session information

You can access the help facility at any time from the prompt. To access help:

• Type g.help

GRASS will print the help screen welcome to the command line interface. The print out will be similar to Figure 1.5 below.

Figure 1.5: GRASS help utility

You can access the GRASS User's Reference Manual entries at any time from the prompt. To access a manual entry:

• Type g.manual

GRASS will print a prompt to the command line interface. This prompt will be similar to Figure 1.6 below.

Figure 1.6: GRASS manual entries prompt

Type the name of the command you would like to see an entry for (this example uses g.gisenv). The print out will be similar to Figure 1.7 below.

Figure 1.7: GRASS manual entries utility

In order to view data, a graphics display monitor must be opened. To view a list of available monitors:

• Type d.mon -L

A listing of monitors will appear in the command line interface that is similar to Figure 1.8 below.

Figure 1.8: Monitor status list

Choose a monitor that has a status of "open" (x0 is used for this example). To start that monitor:

• Type d.mon start=x0
  • start=x#: the name of the monitor to open

A blank monitor will appear that is similar to Figure 1.9 below.

Figure 1.9: A blank monitor

IMPORTANT: GRASS allows for multiple monitors to be open. Additionally, monitors can be split into a number of frames. This tutorial does not address either multiple monitors or frames. Throughout the tutorial only one monitor (with a single frame inside) will be used.

Click the Next button to learn the basic display commands.