UNIX

Files are organized into (main) directories, subdirectories, subsubdirectories, etc.

Unix was created to allow a computer to serve many individuals, and run many programs, at the same time. Although you may be seated at the console of a particular computer, someone else may be logged onto the same computer from a modem or from another workstation, and another person may have left a couple of large computations running on the computer even though she is not actually logged in at the moment.

There are two ways you can run multiple processes on the workstation.

1. The X Window System lets you have many windows running at once. Each xterm, clock, netscape, etc. is a separate process.
2. Furthermore, you can run several operations simultaneously from a single xterm window. All except perhaps one of them would be ``background processes''; only one process can be a foreground process, allowing you to type textual input and get textual output.

The files in your home directory, including those in any subdirectories that you create, belong to you. They may be made readable, executable, or writeable to others as you see fit, using the chmod command. Normally, you don't want your directories and files to be writeable by others.

The basic Unix commands include ``man'', which provides the manual page for a given command, and helps you find the command you want.