CSC128: Introduction to UNIX

Introduction

An Operating System is a set of programs that manage system resources including the CPU, memory, peripherials, data storage, the network, and user information.

In general: The user uses application programs. Those application programs use the Operating System. The Operating System uses the machine.

UNIX is an operating system that is:

• portable
• non-proprietary (anyone can make their own UNIX-like operating system)
• multi-user (can handle more than one user at a time)
• multi-tasking (can run more than one program at a time)
• network-aware (can run programs on remote machines)

Linux is a public licensed operating system, origonally developed by a student in computer science named Linus Torvalds in Helsinki, Finland. The goal of Linux was to have an operating system that was pretty much just like UNIX, but contained none of the licensed code from UNIX versions such as System V Unix from AT&T.

For the purposes of our discussion, as a user Linux and Unix operate, look and feel pretty much the same.

Linux comes in many "flavors", the distribution that we are running here at Parkland is Slackware Linux.

1959:

Multics was developed at the MIT Computation Center, the brainchild of John McCarthy. The idea was to have an operating system that could handle multiple users on a single computer at the same time. This is called time-sharing.

1969:

Bell Laboratories started research on their own time-sharing system, named UNIX as a take on the name Multics.

UNIX was originally written in assembly language (for the PDP-7).

Ken Thompson wrote a portable (machine-independent) programming language called B (which was a subset of BCPL that included a type structure). Dennis Ritchie developed the C language as a modification of B.

One could write a program in C, and could then expect it to run on any computer that a C compiler had been written for. UNIX was re-written in C, and so became very portable.

1975:

The University of California at Berkeley started on its own development path for UNIX that became known as the Berkeley Standard Distribution (BSD).

1983-4:

AT&T releases System V in various versions.

All UNIX systems are based on SysV or BSD or both. UNIX systems based on SysV do some things differenly than those based on BSD. Most experienced users have their preferences; some make theirs heard quite loudly.

POSIX (Portable Operating System Interface for Computer Environments) is the name of an effort to standardize the important aspects of all UNIX systems, in an attempt to retain as much portability between them as possible.

A few current incarnations of UNIX:

• Linux
• FreeBSD, NetBSD, OpenBSD
• BSDi
• Solaris (Sun Microsystems)
• AIX (IBM)
• IRIX (Silicon Graphics (SGI))