| |
|
|
|
|
|
| |
|
|
| |
 |
Introduction
|
|
|
UNIX is a computer operating system.An operating system is the program that controls all the other parts of a computer system, both the hardware and the software. It allocates the computer's resources and schedules tasks. It allows you to make use of the facilities provided by the system. Every computer requires an operating system.UNIX is a multi-user, multi-tasking operating system. Multiple users may have multiple tasks running simultaneously. This is very different than PC operating systems. |
| |
|
|
|
|
UNIX is a machine independent operating system. Not specific to just one type of computer hardware. Designed from the beginning to be independent of the computer hardware. UNIX is a software development environment. Was born in and designed to function within this type of environment. |
| |
|
|
|
|
The "UNIX" trademark, previously owned by AT&T and then deeded to UNIX Systems Laboratories (USL), an AT&T subsidiary, passed to Novell when it acquired USL. After a brief period of negotiations with rival Unix vendors Sun Microsystems, Santa Cruz Operation, International Business Machines, and Hewlett-Packard, Novell granted exclusive licensing rights to the UNIX trademark to X/Open Co. Ltd., an Open Systems industry standards branding agent based in the United Kingdom. |
| |
|
|
| |
 |
History of Unix
|
|
|
UNIX has been a popular OS for more than two decades because of its multi-user, multi-tasking environment, stability, portability and powerful networking capabilities. What follows here is a simplified history of how UNIX has developed. |
| |
|
|
|
|
|
Date
|
Description
|
|
1969
|
Developed at AT&T Bell Labs in Murray Hill, New Jersey, one of the largest research facilities in the world. Created in an environment when most computer jobs were fed into a batch system.
|
|
1975
|
AT&T makes UNIX widely available - offered to educational institutions at minimal cost. Becomes popular with university computer science programs. AT&T distributes standard versions in source form, Version 6 (1975), Version 7 (1978), System III (1981).
|
|
1984 to date
|
University of California, Berkeley adds major enhancements, creates Berkeley Standard Distribution (BSD)
|
|
1984 to date
|
Many Berkeley features incorporated into new AT&T version, System V
|
|
|
|
UNIX has become the operating system of choice for engineering and scientific workstations. |
| |
|
|
|
|
Two variations maintain popularity today, Solaris and Linux. Linux seems to be the future. |
| |
|
|
|
|
|
| |
|
|
| |
|
Unix Components
|
|
|
Unix OS consists of three main components |
| |
|
|
|
|
|
|
|
Each of this, I will be covering in deep. |
| |
|
|
| |
 |
Kernel
|
|
|
Kernel is the core of the UNIX system is Loaded at system start up (boot) and is Memory-resident control program. Kernel manages the entire resources of the system, presenting them to you and every other user as a coherent system. Provides service to user applications such as device management, process scheduling, etc. |
| |
|
|
|
|
Example functions performed by the kernel are: |
|
|
- managing the machine's memory and allocating it to each process.
- scheduling the work done by the CPU so that the work of each user is carried out as efficiently as is possible.
- accomplishing the transfer of data from one part of the machine to another
- interpreting and executing instructions from the shell
- enforcing file access permissions
|
|
|
You do not need to know anything about the kernel in order to use a UNIX system. These details are provided for your information only. |
| |
|
|
| |
|
Shell
|
|
|
Whenever you login to a Unix system you are placed in a shell program. The shell's prompt is usually visible at the cursor's position on your screen. To get your work done, you enter commands at this prompt. The shell is a command interpreter; it takes each command and passes it to the operating system kernel to be acted upon. It then displays the results of this operation on your screen. Several shells are usually available on any UNIX system, each with its own strengths and weaknesses. |
| |
|
|
|
|
Different users may use different shells. Initially, your system adminstrator will supply a default shell, which can be overridden or changed. The most commonly available shells are: |
| |
|
|
|
|
- Bourne shell (sh)
- C shell (csh)
- Korn shell (ksh)
- TC Shell (tcsh)
- Bourne Again Shell (bash)
|
|
|
Each shell also includes its own programming language. Command files, called "shell scripts" are used to accomplish a series of tasks. |
| |
|
|
| |
|
Utilities
|
|
|
UNIX provides several hundred utility programs, often referred to as commands. |
| |
|
|
|
|
Accomplish universal functions |
|
|
- editing
- file maintenance
- printing
- sorting
- programming support
- online info
|
|
|
Modular: single functions can be grouped to perform more complex tasks |
| |
|
|
| |
|
|
| |
|
|
|
|
|
| |
|
|
