CSE 131A - Frequently Asked Questions

Why do we have UNIX groups? And how do we use them?

See the Discussion on Groups

How do I set up my environment?

When you are logged into your account on ieng6 and want to work on CSE 131A, issue the shell command

prep cs131w

This will set up some useful aspects of your computing environment, in particular setting your path and CLASSPATH environment variables. See below, and ~/../public/prepfile, for details.

If you are working in a 2-student team and want group-level access to easily share files, info on setting up a UNIX group is here.

How should I set up my path?

The value of your path environment variable is a list of directories that are searched, in order, for executable files corresponding to a shell command. You can see its current value with the command

echo $path

The prepfile for cs131w puts directories containing the J2SE v1.4 Java interpreter and compiler on your path. Also it adds ~/../public/Tools/bin to your path, which contains some executable scripts that may be useful.

How do I set up my CLASSPATH?

The value of your CLASSPATH environment variable is a list of directories that are searched, in order, for Java classes needed to run particular Java programs. You can see its current value with the command

echo $CLASSPATH

(The standard Java class libraries are always on the CLASSPATH, even if not explicitly shown there.) The prepfile for cs131w puts the JFlex classes (which happen to be archived in a .jar file) and the classes under the java_cup package on your CLASSPATH. This permits, for example, running JFlex with the command

java JFlex.Main filename

What is CVS?  And how do we use it?

CVS is the Concurrent Versions System.  CVS is an industry standard, widely used, free and open system for maintaining a collection of source code files for a project.  It is especially useful if the files are being worked on by multiple programmers; it detects conflicts and automatically keeps backups of previous versions of files.

Complete CVS documentation is available online at cvshome.org.  A good way to get started with CVS is to check out the Minimal Guide to CVS with SSH available online. It may also be useful to do man cvs to view the CVS manual page on ieng6.