The document discusses the UNIX operating system. It describes UNIX as a stable, multi-user operating system developed in the 1960s for servers, desktops, and laptops. The UNIX operating system consists of three main parts: the kernel, the shell, and programs. The kernel allocates resources and handles processes and communications, while the shell acts as an interface between the user and kernel. There are various versions of UNIX that share common features.

1. Presented by
D.Achudhan.
M.Sc Zoology
Department of Animal Health And Management
achukutty2612@gmail.com

2.  Linux operating
system developed by
programming student
Linus Torvalds
 Linus wanted to
develop Unix-like OS
just to experiment with
new 386 computer at
the time...

3.  What Is UNIX?
 UNIX is an operating system which was first
developed in the 1960s.
 It is a stable, multi-user, multi-tasking system for
servers, desktops and laptops.
 UNIX systems also have a graphical user interface
(GUI) similar to Microsoft Windows which
provides an easy to use environment. However,
knowledge of UNIX is required for operations
which aren't covered by a graphical program, or
for when there is no windows interface available,
for example, in a telnet session.

4.  The UNIX operating system is made up of
three parts;
 the kernel, the shell and the programs.
 The kernel of UNIX is the hub of the operating
system:
 it allocates time and memory to programs and
handles the file store and communications in
response to system calls.
 The shell acts as an interface between the user
and the kernel.

5.  There are many different versions of UNIX,
although they share common similarities.
 The most popular varieties of UNIX are Sun
Solaris, GNU/Linux, and MacOS X.
 The UNIX Operating System
 The UNIX operating system is made up of
three parts; the kernel, the shell and the
programs.

6.  A programming language is an artificial
language designed to express computations that
will be executed on a computer.
 Programming languages have a syntax (form)
and semantics (meaning).
 Java and C are example programming
languages

7. 7
• Unix Commands
/home/larry#
•That “something” is called a prompt. As its
name would suggest, it is prompting you to enter
a command.
•Every unix command is a sequence of letters,
numbers and characters. But there are no
spaces.
•When you first log into a unix system, you are
presented with something that looks like the
following:

8. 8
Unix is also case-sensitive. This means that
cat and Cat are different commands.
The prompt is displayed by a special program
called the shell.
Shells accept commands, and run those
commands.
They can also be programmed in their own
language. These programs are called “shell
scripts”.

9. 9
 Unix provides files and directories.
 A directory is like a folder: it contains pieces of paper,
or files.
 A large folder can even hold other folders-directories
can be inside directories.
 In unix, the collection of directories and files is called
the file system. Initially, the file system consists of
one directory, called the “root” directory
 Inside “root” directory, there are more directories, and
inside those directories are files and yet more
directories.
• Storing information

10.  Each file and each directory has a name.
 A short name for a file could be joe,
 while it’s “full name” would be /home/larry/joe.
The full name is usually called the path.
 The path can be divide into a sequence of
directories.
For example, here is how /home/larry/joe is
read: /home/larry/joe
The initial slash indicates the root
directory. This signifies the directory
called home. It is inside the root
directory. The second slash corresponds to the
directory larry, which is inside home.
joe is inside larry.

11. 11
 A path could refer to either a directory or a filename, so
joe could be either.
 All the items before the short name must be directories.
Root Directory
Sub-Directory
homeDirectoryDirectory
larry
joeFileFile
Directory
structure

12.  ls list files and directories
 ls -a list all files and directories
 mkdir make a directory
 cd directory change to named directory
 cd change to home-directory
 cd ~ change to home-directory
 cd .. change to parent directory
 pwd display current dir path

13.  cp file1 file2 copy file1 and call it file2
 mv file1 file2 move or rename file1 to file2
 rm file remove a file
 rmdir directory remove a directory
 cat file display a file
 more file display a file a page at a time
 who list users currently logged in
 lpr -Pprinter psfile print postscript file to named printer
 * match any number of characters
 ? match one character
 man command read the online manual page
for a command

14.  command > file redirect standard output to a file
 command >> file append standard output to a file
 command < file redirect standard input from a file
 grep 'keyword' file search a file for keywords
% grep science science.txt
 wc file count number of lines/words/characters in file
% wc -w science.txt
 sort sort data (numerically or alphabetically)
Ex:
to sort the list of object, type
% sort < biglist
and the sorted list will be output to the screen.

15. TIME
User 1
User 2
User 3
User 4
User 5
User 6
User 7
User 8

16.  The Unix OS is a multi-user OS allowing more
that more person to directly communicate with
the computer.
 Although the OS can only work on one task at
a time, a small piece of time (time slice) is
dedicated to each task or user - this is referred
to as “time-sharing”.
 Time sharing gives the illusion that the CPU is
giving all the users its full attention