Introduction

• A computer system consists ofhardwaresystem programsapplication programs

History of Operating Systems (1)

Early batch systembring cards to 1401 read cards to tapeput tape on 7094 which does computingput tape on 1401 which prints output

Computer Hardware Review (1)

• Components of a simple personal computer

Monitor

Bus

Type of Computers

• Supercomputing: used for scientific computing• Mainframes: used to be primary form of computer, used in centralized

computers, used in businesses for timesharing• Servers: computers used to connect other computers to the internet,

printer, file sharing, etc.• Desktops: Personal Computers• Workstations: More powerful version of the personal computer• Handheld: Smaller operating Systems for handhelds• Real Time: Operating Systems for information that needs to be

updated in real time• Embedded Systems: Systems that are found within another System

History of Operating Systems

• First Operating System

• Originally developed in AT&T Bell Labs (now know as Lucent Technologies)

• UNIX was taken to University of California Berkley leading to the foundation of the Berkeley Standard Distribution

• UNIX then opened up the computer industry to many other UNIX type operating systems and more

• To date, Apple MAC OS X is the most widely used desktop version of UNIX

Types of Operating Systems

• UNIX

• Linux

• Windows

• MAC OS

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Linux

• Free UNIX-type operating system

• Linus Torvalds started creating in 1991

• Started out as MINIX then formed into Linux

• Continuously updated• Popular among college students• Intended for small servers,

workstations, desktops, and handhelds

• Cost: Free

What is Unix?

A fully featured modern operating system

It is available in a variety of “flavors.”

It’s comprised of simple tools that perform a single function well.

These tools can be used together to perform complex tasks.

A Little History First: UNIX

• Initial design by Ken Thompson, Dennis Ritchie and others at AT&T's Bell Telephone Laboratories (BTL) in 1969: 32 years ago!

• AT&T made the source available to Universities for research and educational use.

• 1973 UNIX was rewritten in C resulting in Version 4.The C language was also originally designed and

developed for use on the UNIX system by Dennis Ritchie

C was evolved from 'B', developed by Thompson.

Commercialization• Interactive Systems first commercial (1977)• Microsoft and SCO release XENIX (1980)• 1982 Bill Joy left Berkeley and founded Sun

Microsystems.SunOS originall based on BSD 4.2SunOS 5 (Solaris 2.X) was a collaborative effort based on

System V, release 4 (SVR4).

• AIX from IBM• HP/UX from Hewlett Packard Corporation• ULTRIX from Digitial Equipment Corporation, followed

by DEC OSF/1. DEC purchased by Compaq

Unix is Made Up of

ProcessesProcesses• Running ProgramsRunning Programs

User owned User owned System ownedSystem owned

FilesFiles• Regular Files: Regular Files:

– DataData

– Executables <-- usually start a processExecutables <-- usually start a process

• Directory FilesDirectory Files– Contain other files and directoriesContain other files and directories

• Special FilesSpecial Files

Our View of the World as Users

Unix Shell

Your ShellYour Shell

A shell is a process A shell is a process that acts as an that acts as an interface to the OS. It interface to the OS. It allows the user to run allows the user to run programs individually programs individually and together to and together to accomplish a task.accomplish a task.

Fred Kuhns ( ) CS523S: Operating Systems

Simple Unix Directory Structure

/

usr etc home bin var ...

local bin ... class grad ugrad ...

mmscott jpeckhar...

Your First Command

• Syntax: man topic

• man provides online documentation on nearly every standard command and configuration file.

• Optional Syntax: man -k keyword

• man man for more details

Man(manual) -- Documentation is your friend

Special Directories

Home Directory• /home/grad/jpeckhar

• ~jpeckhar

• ~

• A user generally has permission to freely manipulate files within this directory and its children.

• Users start with their home directory as their pwd when they login.

Changing Directories

• The cd(Change Directory) command is used to change directories

• cd path

• Paths can be relative or absolute

• pwd reports present working directory

• cd when entered by itself sets the pwd to the user’s home directory.

Other File System Utilities

• ls Lists all files in a directory

• cp Copies files

• mv Moves files

• rm Deletes files

• mkdir Makes directories

• rmdir Removes directories

Basic Syntax

• ls ls

• cp cp source dest OR cp source … dir

• mv mv source dest OR mv source … dir

• rm rm file

• mkdir mkdir new directory name

• rmdir rmdir directory to be removed

Using Other Commands Syntax: command file

• cat Echos file contents to the screen

• grep Searches a file for a string

• more Echos a file a line at a time

• less Same as more but more features

• wc Counts the words in a file and more

• sort Sorts the contents of a file

Pipes

• Pipes connect stdout of one command to stdin of another comand. i.e.

• ls | less

• cat student_list | grep senior | sort

I/O Redirection

• I/O redirection allows the user to change where input to a command or output from a command goes to/comes from.

• cat student_list > outfile

• program < infile

• program < infile > outfile

Standard File Handles

Every Unix process automatically comes with three file handles or descriptors.

These are:Standard Input (stdin)

Keyboard

Standard Output (stdout) Display

Standard Error (stderr)Display (unbuff)