Getting Started

Once you have an account on positron.truman.edu – the student computer that runs IDL – you will need to log on and use IDL. I'll give you the basics here, plus some elementary UNIX commands so you don't feel lost on a non-Windows machine.

The easiest way to run things is to log in directly onto the big SGI workstation located in the physics students' computer lab, MG 3008. This will also allow you to use a large monitor, which is nice.

Alternatively, you can use a program called "XWin-32" which is part of the standard student image on campus computers. Start XWin-32. You will find that its effect will be to produce a small "X" icon on the bottom right of your screen. The first time you use it, you will need to define a "session." Right-click on the X icon, and choose "Xconfig." Define a new session (use the wizard if you like), just be sure to use "XDMCP" as your connection mode, and choose "Query." Enter "positron.truman.edu" as your host name. Name your session (something like "idl") and save it. From now on, left-clicking on the X icon will bring up this session name, and choosing it will connect to the SGI machine.

Once you're logged in, you can use some basic UNIX commands to get around and manage your files. You issue these commands from a console (or "xterm") window.

First, play with "ls" – this gives you a directory listing. "ls -l" is a long format listing. Here is an example screen shot listing the files in my "student-research" directory. If you're just starting out, you won't have too many files, so "ls" will not list much.

Then, manipulate files. Say you have a file called "a.txt". To make a copy called "b.txt", just use "cp a.txt b.txt". To change its name to "c.txt", use "mv a.txt c.txt". And to remove a file, use "rm a.txt".

Now play with directories. To create a subdirectory "a" of the directory you're currently in, use "mkdir a". To change your directory to "a" say "cd a". To find out where you are, use "pwd". To move one up one directory, use "cd ..". And to remove a directory, say "rmdir a" in its parent directory.

Note the last command in the screen capture, "idlde". This starts IDL (it stands for IDL Development Environment). Now you're ready to program!