Unix/Linux Tutorial

Unix/Linux Tutorial Overview

Welcome to Unix/Linux Tutorial by Linux Experts. The objective of these tutorials is to provide an in-depth understanding of the Linux Operating System. In these tutorials, we will cover topics such as Architecture, OS Commands, Vi Editor, and File Permissions. We will also cover advanced topics such as Scheduling Jobs, User Administration, Disk Partitioning, Package Management, and Troubleshooting of common issues.

In addition to the free Linux tutorials, we will also cover common interview questions, issues, and how to's of the Linux operating system.

Index

• Features of UNIX/LINUX
• UNIX Introduction
• UNIX Commands
• System Usage Accounting Services in UNIX
• History and Features of UNIX
• Daemon process in UNIX
• Understanding of Unix Programs
• Unix System Architecture And Its Explanation
• Functional layers & Models in Unix
• Architecture of UNIX
• Working With Wait() In UNIX
• Unix Shell Scripting

Introduction to UNIX

• UNIX is a CUI Operating system.
• LINUX is not just for UNIX wizards. LINUX is a clone of O/S.
• Linux is the most important achievement of free software, it has been developed for business, education & personal productivity.
• Everyone has to start somewhere, and Linux administrators and engineers are no exception. Of you have purchased this book, I imagine that your goal is to pass the Red Hat exams (RHCSA & RHCE) while acquiring or improving your current Linux skills.
• These Linux skills and commands are all essential for knowing how to work with Linux, not just Red Hat.

Operating System(O/S)

• The operating system is an interface between user & computer (or) it is system software.
• The operating system is the most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs.
• Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.
• It is classified into two types.

Single user systems: Provides a platform for only one user at a time. They are popularly associated with the DeskTop Operating System which runs on standalone systems where no user accounts are required.

Example: DOS

Multi-User Systems: More than one user can access the same system resources (CPU, applications, memory, printers ………etc) at the same time known as multiuse.

Example: UNIX, LINUX

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Feature of Linux

Multiuser: A multi-user Operating system allows more than one user to share the same computer system at the same time.

Multi-Tasking: More than one program can be run at a time. The main concept of multitasking is maximum utilizing CPU resources

Open System: The UNIX is open source code i.e Any user can modify Unix open-source code according to there ideas and requirements

• Using UNIX open source codeSun Micro Systems+ Adding additional features =Sun SalariesIBM+Adding additional feature  =  IBM-AIXHP+Adding additional feature= HP=UXSunta Curuz + Adding additional feature= SCO-UnixSilicon Graphics   +Adding additional feature=   IRIXMicro Soft+Adding additional feature  =    xenix

• Any operating system developed based on UNIX open-source code known as flavors of UNIX
• The Linux was given to GPL (General Public License) Organized by GNU.
• Linux Torvalds, who was then a student at the University of Helsinki in fin land, developed Linux in 1991. Linux is also an open system

Distributors of Linux

• Red Hat
• Suse
• Ubuntu
• Puppy
• Slackware
• Centos
• OEL
• Fedora
• White box
• Mandrake

Security: One of the most valued advantages of Linux over the other platforms lies with the high-security levels it ensures. Every Linux user is happy to work in a virus-Free environment and use the regular virus – prevention time needed when working with other operating systems for another more important task.

--> UNIX/LINUX has given two levels of securities.

• System-level Security: It's controlled by the system administrator.
• File-level Security: It's controlled by the owner of the file.

Portability: Portability means Independent of hardware & processors

Communication: The main concept of communication facility Exchanging of information or files from one user account to another user account.

Programming Facility: UNIX o/s provides shell. Shell works like a programming language. It provides commands and keywords.

Script Language	Programming Language
It is an interpreter based language.	Compiler based language
Interpreter Converts high level	The whole program is a single short into machine language.
Doesn’t create .exe files	Create .exe files
No need to compile the program.	Need to compile the program
It takes fewer lines of code	Takes numerous lines of code.
Reduces cost of maintenance	Increases the cost of maintenance.

Help facility: It is a beautiful feature of UNIX/ LINUX Operating systems. Don’t know the information about the given command just go through the helpline.

Example:                    

#Man <command name>

(or)

#info <Command name>

(or)

#<command name> --help