Operating Systems Every computer has two fundamental components: hardware and software The term hardware refers to the physical components inside a computer A computer can have many different pieces of hardware Chapter 1

Operating Systems Software refers to the sets of instructions (programs) that understand how to use the hardware of the computer in a meaningful way More specifically, software programs use hardware to manipulate data (or files) and perform useful tasks A program is a file stored on your computer, whereas a process is that file in action, performing a certain task Chapter 1

Operating Systems Two different types of programs are executed on a computer: Applications, which are programs designed for a specific use and that we commonly interact with, such as word processors, computer games, graphical manipulation programs, and computer system utilities The operating system (OS) software, which consists of a series of software components used to directly control the hardware of your computer Chapter 1

Operating Systems The operating system carries out many different tasks by interacting with many different types of computer hardware Chapter 1

Operating Systems Command-line user interface: prompt where you must type a command to tell the operating system what to do, or it can be a graphical user interface (GUI): consists of a series of visual depictions of tasks known as icons that you may use to control the operating system system services: programs that handle system-related tasks such as printing, scheduling programs, and accessing the network Chapter 1

The UNIX Operating System UNIX is an operating system that runs a variety of different applications Similar to other operating systems, the UNIX operating system loads into computer memory when you first power on your computer and initializes all the hardware components Chapter 1

UNIX Provides a Standard Interface The standard GUI in UNIX is the Common Desktop Environment (CDE); however, some UNIX flavors may use other GUIs instead such as MOTIF, GNU Object Model Environment (GNOME), and K Desktop Environment (KDE) Chapter 1

UNIX Provides a Standard Interface In addition, all UNIX flavors offer a text-based command-line interface where you may type commands that ultimately perform useful commands on the system The UNIX operating system enables multiple users to access the system simultaneously using different user interfaces, hence, we refer to UNIX as a multi-user operating system Chapter 1

UNIX Runs Many Applications UNIX was designed as a powerful application server that can run for long periods of time without being shut down It has the capability to manage thousands of applications at the same time; as a result, it is referred to as a multitasking operating system The most common applications used on UNIX computers include those listed on page 5 of the textbook Chapter 1

UNIX Is Customizable UNIX supports the Shell and Perl programming languages, which can be utilized to automate tasks or create custom tasks that are then invoked as needed In UNIX you can simply write a short Perl script that uses common UNIX commands and programs together to achieve this task in only a few minutes Most UNIX configurations present hundreds of small utilities, which, when combined with Shell or Perl programming, can quickly and easily make new programs that meet many business needs Chapter 1

UNIX Roles All of the features of the UNIX operating system enable it to function in different environments in a variety of roles, including: Network/Internet server File and print server Application server Supercomputer Scientific workstation Office workstation Chapter 1

The History of UNIX Much of the research and development that led to the UNIX operating system came from the Multiplexed Information and Computing Service (MULTICS) project that was started in 1965 by the Massachusetts Institute of Technology (MIT), General Electric (GE), and AT&T Bell Laboratories Ken Thompson, one of the original researchers on the MULTICS project, continued to experiment with operating system development after the project was abandoned In 1969, he developed an operating system that ran on the Digital Equipment Corporation (DEC) PDP-7 computer Chapter 1

The History of UNIX Dennis Ritchie invented the C programming language that was used on Ken Thompson’s UNIX operating system The C programming language was a revolutionary language at the time AT&T Bell Laboratories continued to develop new versions of UNIX and sold the rights to use them to several different companies that in turn marketed their own type of UNIX; these types are commonly referred to as different UNIX flavors By the late 1970s, BSD UNIX was adopted as the primary operating system for the U.S. Department of Defense Advanced Research Projects Agency (DARPA) Chapter 1

The History of UNIX In 1982, AT&T released System III UNIX (System I and II never existed), and the University of California at Berkeley released BSD UNIX version 3 Both of these new versions of UNIX were based on version 7 of the AT&T Bell UNIX, but they were very different in philosophy and appearance By 1983, AT&T released System V UNIX (System IV was never released), resulting in two distinct streams of UNIX at the time; the AT&T System V stream and the BSD stream The Institute of Electrical and Electronics Engineers, Inc. (IEEE) created a standard called Portable Operating System Interface (POSIX) in 1986 to address how operating systems interface with application programs and to provide a way to standardize many of the different UNIX flavors that appeared during this time Chapter 1

The History of UNIX In 1991, a Finnish student named Linus Torvalds released a free version of UNIX called Linux Since then, Linux has been freely and aggressively developed by volunteers worldwide and is one of the most common UNIX operating systems used today In 1998, System V Release 5 evolved with the introduction of Santa Cruz Operations (SCO) UnixWare 7, and, in 2000, Apple Computers Inc. introduced the first user-friendly version of UNIX called OS/X Chapter 1

Common UNIX Flavors Chapter 1

The UNIX Development Timeline Chapter 1

Solaris Solaris is one of the oldest UNIX flavors available Bill Joy, the co-founder of Sun Microsystems, was the original developer of BSD UNIX in the 1970s Solaris was initially called the SunOS when it was released by Sun Microsystems in 1982 and is widely used in academic and business environments today, primarily on the SPARC and Ultra SPARC architectures Chapter 1

Solaris Sun Microsystems and Solaris have achieved great fame in the past two decades for creating technologies that have become standard across all UNIX; two of these include the Network File System (NFS) for sharing data files between UNIX computers and the Network Information System (NIS) for sharing configuration files between UNIX computers Chapter 1

Hewlett-Packard UNIX (HP-UX) Since HP-UX was first released in 1986, it has become one of the most popular UNIX flavors in large-scale computing environments HP-UX runs primarily on the PA-RISC architecture, but newer versions also run on the Intel Itanium architecture Chapter 1

UNIX Resources By far, the easiest way to locate resources on any topic is by using a search engine such as http://www.google.com/ where you can simply put in a phrase representing what you are searching for and receive a list of Web sites that contain relevant material Each UNIX flavor is maintained by a certain company or organization as discussed earlier in this chapter Because UNIX has been common in academic environments since the 1970s, most university Web sites offer UNIX tutorials and other useful information such as Frequently Asked Questions (FAQs) Chapter 1

UNIX Resources Web sites host valuable information, but most do not provide any means for users to communicate with each other This functionality is provided by Usenet, which enables users to post messages in forums called newsgroups and enables other users to read and reply to those messages Newsgroups forums are grouped according to topic Posting to a newsgroup is often a very quick way to find the solution to a problem, because people who read the posting are likely to have had the same problem and found a solution Chapter 1

Summary POSIX and the sharing of ideas have standardized most features of different UNIX flavors Often the largest differences between UNIX flavors relate to system hardware terminology, whereas most commands are identical between UNIX flavors A wide variety of documentation and resources is available for UNIX in the form of Internet Web sites, FAQs, and newsgroups Certification is a valuable means of demonstrating knowledge and ability to industry Chapter 1