Linux Basics | Core Linux | ppts | Introduction | demo | course free

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Outline
 What is an Operating Systems
 History of UNIX
 Unix Principles
 ARCHITECTURE OF UNIX
 FILE SYSTEM HIERARCHY
 BASIC COMMANDS IN UNIX

WHAT IS OPERATING SYSTEM?
 Operating system is an interface between user and the computer
hardware. The hardware of the computer cannot understand the
human readable language as it works on binaries i.e. 0’sand 1’s. In
such case we need an interface which can translate human language
to hardware and vice-versa for effective communication
 Requirement to create an operating system
source code +applications=kernel
kernel+ software=os

HISTORY OF UNIX
 In 1960 1st operating system is MULTICS (multiplexed information computer
service)at AT & T bell lab
 Ken Thompson developed UNIX in 1969 so he could play games on a scavenged DEC
PDP-7. With the help of Dennis Ritchie, the inventor of the “C” programing language,
Ken rewrote UNIX entirely in “C”
 In 1974, the OS was licensed to universities for educational purposes.
 Over the years, hundreds of people added and improved upon the system, and it
spread into the commercial world.

 GNU project started in 1984 by Richard Stallman.

During the late 1980’s there were several of
commercial implementations of UNIX:
 Apple Computer’s A/UX
 AT&T’s System V Release 3
 Digital Equipment Corporation’s Ultrix and OSF/1 (renamed to DEC UNIX)
 Hewlett Packard’s HP-UX
 IBM’s AIX
 Lynx’s Real-Time UNIX
 NeXT’s NeXTStep
 Santa Cruz Operation’s SCO UNIX
 Silicon Graphics’ IRIX
 SUN Microsystems’ SUN OS and Solaris and dozens more.

UNIX PRINCIPLES
Everything is a file:- UNIX system have many powerful utilities
designed to create and manipulate files. The UNIX security model is
based around the security of files. By treating everything as a file, you
can secure access to hardware in the same way as you secure access to a
document.
Configuration data stored in text: - Storing configuration in text allows
an administrator to move a configuration from one machine to another
easily, provide the ability to roll back a system configuration to a
particular date and time.

Linux orgins
 Linux was developed in 1991 by Linus Torvalds and a band of
programmers who voluntarily developed the core program of the
system, the kernel. That program was originally compatible for
another operating system called Minix .
 When Linux Kernel combined with GNU applications, complete free
UNIX like OS was
developed.
Eg: Redhat, CentOS, SuSe, Fedora,
Ubuntu, Gentoo

ARCHITECTURE OF UNIX

FILESYSTEM HIERARCHY

Basic commands
 Cat find command
 Vim soft&hard link
 Mkdir
 Cp,mv,rm,rmdir
 Grep
 Filter commands
 i/o redirection
 File permission

Command to create files:
 1.cat > file1 to create a file and data to file
 2.cat file1  to see file information
 3.cat >> file1  to add data to already the
extisting file
 Touch command:
 1.touch file{1..100}  to create multipul files
but empty files
 Create directory:
 mkdir ktdir to create a directory

1. cp file ktdir
2. cp –rfvp ktdir ktdir2
3. mv file ktdir
4. mv ktdir ktdir2
5. mv oldfilename newfilename
6. mv olddirectory newdirectory
7. rm –f filename
8. rmdir dirname
9. rm –rf dirname

Vim editor:
1.Command mode(edit)
 2.Inset mode(inter data)
 3.Extend command mode(save the file)

 Command mode keys:
 gg, G, dd, 5dd, u, yy, 4yy, p, P, x, U
 Insert mode:
 i, o, a ,A
 Extend command mode:
 Esc+shift+:+wq
 Esc+shift+:+X
 Esc+shift+:+se nu
 Esc+shift+:+se nonu

soft link Hard link
SHORTCUT FILE BACKUP FILE
if original file is deleted, link is broken
and data is lost
If original file is deleted then also link
will contain data
Files,directorys files
Inode no. of source and link file is
different
Inode no. of both file is same

Filter commands:
1. less
2. more
3. head
4. tail
5. sort
6. cut
7. sed

Find command:
 find / -name file1
 find / -inum file1
 find / -group file1
 find / -user file1
 I/O REDIRECTION:
Redirection is a process where we can copy the output of any
command(s), file(s) into a new file. There are two ways of redirecting
the output into a file.
cat file1 >> file2
cat file1 > file2

FILE PERMISSIONS:
 1. Symbolic method
 2. Absolute methods
 Absolute methods
Permissions are applied on three levels:-
Owner or User level(u)
Group level(g)
Others level(o)
Syntax:
Chmod u+rw,g+wrx,o+wx file/dir
+ adding, -substract, = overwritting

Symbolic method:
Read = 4
Write = 2
Execute = 1
User,group,others
Syntax:
1. Chmod 675 file/dir

Umask
022
Directory: 777-022 = 755
Files: 666-022 = 644
Umask 002
Directory: 777-002 = 775
Files: 666-002 = 664

Questions?

THANK YOU
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Linux Basics | Core Linux | ppts | Introduction | demo | course free

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