Transcript Traditional UNIX kernels

Introduction
• A computer system consists of
 hardware
 system programs
 application programs
History of Operating Systems (1)
Early batch system
 bring cards to 1401
 read cards to tape
 put tape on 7094 which does computing
 put tape on 1401 which prints output
Computer Hardware Review (1)
Monitor
Bus
• Components of a simple personal computer
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
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• 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
Go on to next page
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 4.2
 SunOS 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
Processes
• Running Programs
User owned
System owned
Files
• Regular Files:
– Data
– Executables <-- usually start a process
• Directory Files
– Contain other files and directories
• Special Files
Our View of the World
as Users
Your Shell
Unix
Shell
A shell is a process
that acts as an
interface to the OS. It
allows the user to run
programs individually
and together to
accomplish a task.
Simple Unix
Directory Structure
/
usr
etc
local bin ... class
Fred Kuhns ()
home
grad
bin
ugrad ...
mmscott jpeckhar...
CS523S: Operating Systems
var ...
Your First Command
Man(manual) -- Documentation is your friend
• 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
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
• rm
cp source dest OR
cp source … dir
mv source dest OR
mv source … dir
rm file
• mkdir
mkdir new directory name
• rmdir
rmdir directory to be removed
• mv
Using Other Commands
Syntax: command file
• cat
• grep
Echos file contents to the screen
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)