Linux Environment- Linux Basics

TRINITY INSTITUTE OF PROFESSIONAL STUDIESSector – 9, Dwarka Institutional Area, New

Delhi-75Affiliated Institution of G.G.S.IP.U, Delhi

BCALinux Environment

BCA306

Linux BasicsKeywords: Linux, Unix,

Characteristics and Architecture

TRINITY INSTITUTE OF PROFESSIONAL STUDIESSector – 9, Dwarka Institutional Area, New Delhi-75

An operating system is the software that provides the interface between the hardware of a computer system and the applications programs that are used on it.

Operating System


Introduction to Linux

• A free Unix-type operating system originally created by Linus Torvalds with the assistance of developers around the world. • The source code for Linux is freely available to everyone.• Has the X Windows GUI , including many of the tools

that Windows users are familiar with such as,– A file manager– A Window manager– A help system– A configuration– …….


• Requiring less system resources. A Linux based system can operate smoothly on a 386 or 486.

• Application software support– Office applications: Corel WordPerfect Office 2000 for

Linux Deluxe– Graphics tool: Gimp– Browsers: Netscape Communicator 4.75, Opera browser

• Multi-user, Multitasking, Multiprocessor• Coexists with other Operating Systems • Runs on multiple platforms

Introduction to Linux . . contd


Main Characteristics

• Multitasking– Linux supports true preemptive multi-tasking. All processes run

independently of each other.• Multi-user access– Linux allows number of users to work with the system at the same

time.• Multi-processing– Operating system can distribute several applications across several

processors.• Architecture Independence– Linux can run on several hardware platforms from amiga to PC to DEC

Alpha workstations.



• Demand load executables– Only those parts of a program actually required for execution are

loaded into memory.Copy-on-write principle is used when a new process accesses memory in write mode.

• Paging– Linux uses paging to use the physical memory efficiently.

• Dynamic cache for hard disk– Linux dynamically adjusts the size of cache memory in use to suit

the current memory usage situation.• Shared Libraries– Libraries are collection of routines needed by a program for

processing data. They are loaded into memory only when the process is run.



• Support for POSIX 1003.1(Portable Operating System Interface for Unix) standard– POSIX 1003.1 defines a minimum interface to a unix type

operating system. Linux fully supports it• Various formats for executable files– Linux can execute programs from other unix system conforming

to iBCS2(Intel Binary Compatibility Standard (ibcs2)) standard.

• Memory protected Mode– Linux uses processor’s memory protection mechanisms to

prevent the process from accessing memory allocated to system kernel or other processes.

• Support for national keyboards, fonts



• Different file systems– Linux supports variety of file systems. Most common being

Second extended (ext2) file system. Others being ms-dos file system, VFAT file system for accessing windows/ms-dos,ISO for accessing CD-ROMS, NFS for accessing the file systems

of other unix systems etc.

• TCP/IP, SLIP and PPP support– Linux can be integrated into local unix networks. All network

services, such as NFS and remote login can be used. SLIP and PPP support the use of TCP/IP protocol over serial lines i.e. internet via pubic telephone network.


- Surrounding the kernel and acting as a user interface to the Linux operating system- Command language interpreter - Interprets the command users enter - Selects and runs the command or program - Provides the results to the screen or file as directed by the command-C shell, Bourne shell, Korn shell

Linux functionally organized at three levels

shell

Tools and applications

The main part of operating system, and responsible for controlling system resources. -Loaded into memory when the system boots-Process control and scheduling-Memory management-Device I/O-System error handling-User programs requesting services from the kernel through system calls-Hardware devices getting kernel response through interrupts

kernel

offering additional functionality to the operating system


What is Kernel?

Kernel is heart of Linux Os. It manages resource of Linux Os. For e.g. Facility to store data, print data on printer, memory, file management etc .Kernel decides who will use this resource, for how long and when. It runs your programs (or set up to execute binary files).The kernel acts as an intermediary between the computer hardware and various programs/application/shell


What is Shell?

An interface between the Linux system and the user• Used to call commands and programs• An interpreter• Many available (bsh; ksh; csh; bash; tcsh)• A shell is any program that takes input from the user,

translates it into instructions that the operating system can understand, and conveys the operating system's output back to the user.


What is Shell Script ?

Shell Script is series of commands written in plain text file.

Shell script can take input from user, file and output them on screen.

Useful to create our own commands. Save lots of time. To automate some task of day today life. System Administration part can be also

automated.


13

THANK YOU

Education

Linux Environment- Linux Basics