The lab comprises a cluster of workstations running Debian Linux with a central file server. The machines are located in SC 347 and are also available for remote login using SSH and VNC (see remote login to the right).

The lab is used primarily for upper-level Computer Science and Computer Information Systems classes but is also available for general use by other Wartburg students. If you would like an account contact Dr. John Zelle.

The default desktop environment on these machines is KDE, but others are also available. Standard software includes programming environments for C, C++, Java, Python, Perl, Prolog, Scheme, and COBOL as well as text-formatting utilities (Latex), editors (emacs and vi) and a host of productivity programs, image viewers/editors, and of course games.

Selecting a Shell
To some extent, the "feel" of interacting with a Unix system depends on the command interpreter or "shell" that you are using. Different Unix systems have different shells, and users can often select among a number of different shells to suit their own tastes.

The most commonly used shell in the Linux world is "bash".  It is an enhanced version of a traditional shell known as the Bourne shell.  Bash is the "Bourne-again shell".  Some other common shells are based on the original "C" shell (csh).

Shell Features (tcsh and bash)

Command recall.
You can cycle through previous commands using the up and down arrows.

Command/filename completion.
If you type the first few characters of a command or file/directory name and then press the tab key, the shell will attempt to complete the command or name. If there is more than one valid completion, the shell will complete the command up to the ambiguity. Pressing tab again will show the possible completions.

Filename wildcards.
You can specify a "set" of files using "*" to represent a sequence of characters. For example, "foo*" matches all the files starting with "foo".

echo $<variable> display the contents of the variable. Example: "echo $PATH"

setenv <variable> <value> (c-shells only) set the value of a variable. To add a new directory to a path, a c-shell user would do something like "setenv PATH ${PATH}:/home/myfiles/bin". The ${PATH} is the old value of PATH and causes the new directory to be appended.

unsetenv <variable> (c-shells only) clears out an environment variable. For example, for a text-based login session, a user might to "unsetenv DISPLAY" so that certain commands (e.g. emacs) do not try to create a window.

<variable>=<value>;export<variable> (Bourne-shells) sets the value of an environment variable. Note there should be no spaces around the "=". Example: "PATH=${PATH}:/home/myfiles/bin ; export PATH"

<variable>= to unset a variable. Example "DISPLAY="

Sometimes there are some variables that we always want to set. We can customize the environment automatically by placing shell commands in a file that is automatically consulted when the shell starts. For bash,  the commands in ".bash_profile" are performed on login, and those in ".bashrc" are performed whenever a new shell is started.. For c-shells, the commands in ".login" are performed when you login, and those in ".chrc" are performed each time you start a shell. Usually, you would modify the commands in .login. Note these configuration files start with ".", so they are hidden files (see section on files).

Job Control
To execute a command, simply type the name of the command at the shell prompt. For example, to start the emacs text editor, type: emacs <enter>. When the command has finished executing, you will get back the shell prompt. Putting an "&" at the end of a command causes it to run in the background. That is, the shell prompt returns immediately so that more commands can be issued. The background command will run concurrently with any subsequent commands. In this fashion, it is possible to be running multiple "jobs" at the same time. Here are some commands for manipulating multiple jobs:

jobs list the currently running jobs.
<ctrl>-z suspend the current foreground job.
bg restart a suspended job in the background.
fg restart a suspended job in the foreground.
kill %<number> kill (terminate) the job with the given number (obtained from "jobs").
kill -9 %<number> terminate with extreme prejudice.

Files and Directories
Unix maintains a tree-structured directory system. When you log in, you are automatically placed in your "home" directory. You can make subdirectories to organize your files. In referring to directories, there are some special conventions:

'~' represents your home directory (can also use '$HOME')

'.' represents the current directory.

'..' represents the parent of the current directory.

mkdir filename create a new (sub)directory

cd directory

Change directory

cd .. change to parent directory

more filename display contents of file one page at a time

cat filename display contents of entire file

rm filename delete the specified file

exit leave current command shell. At top-level, this logs you out

passwd change password on local machine. In the UCL, this command is an alias for yppasswd

yppasswd change your password on central password server

man command display manual page entry describing the command

man -k term display commands related to this term

xterm (or konsole) & start up a graphical terminal (only used under X-windows)

Current machines available:
- molly.wartburg.edu
- neon.wartburg.edu
- loach.wartburg.edu
- clown.wartbur.edu
- guppy.wartburg.edu
- danio.wartburg.edu
- barb.wartburg.edu
- gourami.wartburg.edu
- cichlid.wartburg.edu
- oscar.wartburg.edu
- lion.wartburg.edu
- dojo.wartburg.edu