unix ppt 3892
TRANSCRIPT
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Operating Systems
The RelationshipBetween Hardware &Software
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Goals
Understand what an operating system is
Become familiar with several different operating systems
Learn about the important features of an operating system,including file management
Understand the Unix Operating System and tools associatedwith Unix
Understand Unix Permissions
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Why Study Operating Systems?
Understand therelationship betweenhardware & software
Understand futureOperating Systems
Understand powerfultools to help you in yourcomputer use
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What is an Operating System?
Software
Controls the relationshipbetween all othersoftware and hardware
Other Roles
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The Two Major Types of OSs
Letters with symbols, such asC:\>
Type what you want thecomputer to do - theCOMMAND
Type it correctly DOS and UNIX, but they do
have GUIs available
Pictures with descriptivewords
Click a picture to start aprogram
Point and Click
Much easier to move thepointer with the mouse andCLICK on a picture, than toremember COMMANDS
Window 3.1, Windows 95, MACO/S
http://klingon.cs.iupui.edu/~micenogl/os9a.htmlhttp://klingon.cs.iupui.edu/~micenogl/os9b.htmlhttp://klingon.cs.iupui.edu/~micenogl/os9c.htmlhttp://klingon.cs.iupui.edu/~micenogl/os9d.htmlhttp://klingon.cs.iupui.edu/~micenogl/os9e.htmlhttp://klingon.cs.iupui.edu/~micenogl/os9e.htmlhttp://klingon.cs.iupui.edu/~micenogl/os9e.htmlhttp://klingon.cs.iupui.edu/~micenogl/os9e.htmlhttp://klingon.cs.iupui.edu/~micenogl/os9d.htmlhttp://klingon.cs.iupui.edu/~micenogl/os9c.htmlhttp://klingon.cs.iupui.edu/~micenogl/os9b.htmlhttp://klingon.cs.iupui.edu/~micenogl/os9a.html -
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So, What Does an OS Do?
Controls the INPUT,OUTPUT, and PROCESSING
activities for the computer It is the BOSS of what
happens in the S/W, the H/W,and between the S/W andH/W
High-quality O/S can make
your computer more effectiveand efficient
Good OS makes thecomputer easier to use andmore efficient
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The Roles of an Operating System
A Traffic Cop
A CommunicationSystem
A Box of Tools
A Self-Starter
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OS as a Traffic Cop
Controls the resourcesof the computer
Resources include:memory, file storage,and CPU
Multitasking is possible
on new computers
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OS as a Communications System
Helps all of theHARDWARE
componentscommunicate with eachother
Helps the software
communicate with thehardware
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OS as Toolbox
Several utility programsincluded with an O/S
File Management
Memory Management
AppearanceManagement
Networking Tools
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OS as a Self-Starter
Takes over just afterbooting
Checks to see allhardware is present
Mechanisms for HardBoot & Soft Boot
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Flavors of Operating Systems
Marketed by Microsoft in 1981
Command-Line
Inspired by UNIX
Used on computers with the Intel Chip
DOS
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Flavors of Operating Systems
Developed by Apple in 1984
Successful Marketing Campaign
Changed the ideas about ease of use
Largely ignored by the PC world
Apple Macintosh
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The 1984 Macintosh Ad
Premiered during 1984Superbowl
Played just once
Launched a new era ofadvertising
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Flavors of Operating Systems
Developed in 1992
First commercially successful GUI for PCs
Actually not an Operating System
Technically a shell that runs on top of DOS
Windows 3.1
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Flavors of Operating Systems
Developed in 1995
Introduced the idea of the desktop for PCs
Independent Operating System
Made networking easier
Windows 95/98/2000
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Flavors of Operating Systems
Developed in 1995
Introduced the idea of the desktop for PCs
Independent Operating System
Made networking easier
Windows 95/98/2000
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Flavors of Operating Systems
Developed by Bell Labs in 1969
Command-Line OS
Offered File Sharing
Offered Process-Sharing
Unix
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Introducing Unix Commands
Command Line OS
Issue commands from a command prompt:phoenix{jstudent}/:
Unix is case sensitive
Commands are typed in lowercase:cp (copy) is NOT the same as Cp or CP
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Unix Shells
Unix has a number of shells which help the userinteract with the Operating System Kernel (the main
program that stays resident in memory and executesOS commands)
Shell Examples: Bourne Shell
Korn
Bash
TCSH
CshC-shell The default shell for Phoenix
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Command Syntax
Case sensitive! All commands are lowercase
General Format:command [switches] parameter1 parameter2
Example:ls l *.html
Command
FlagArgument
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Correcting Typographical Errors
DEL key removes the character to the left (in
some Telnet clients, BACKSPACE will also dothis)
To erase:
C-w Erases previous word
C-u Erases an entire line
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Directory Structures
Unix paths begin with a forward slash
The initial forward slash (/) represents the rootdirectory
An absolute path begins at the root:/home/jstudent/public_html/
A relative path indicates location relativetoyour present working directory:../images/
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More on Directories
The command pwd will return the directory
name in which you are currently working The directory that represents your personal
section of the server is called your homedirectory
The root directory is parent directory to allother directories (usually restricted use)
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Directory Notation
/ - represents a directory
/. represents the current directory
/.. represents the parent directory
/~ - represents a users home directory
Creating directories
No spaces in a name Use _ or camel casing to name directories
Case sensitive (usually in lowercase, with camel casing)
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Creating a Directory
Use the mkdir command:mkdir campingImages
Command
Required argument:name of the directory(uses camel casing)
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Naming Files
Extensions
Determine the type of the file
Examples
*.txt
*.html
*.cgi
*.gif
*.jpg
Filenames that begin with . are hidden and will not
appear unless a special directory command is used.
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File & Directory Permissions
ls l command will show full details:drwxr-xr-x 2 rmolnar staff 512 Sep 18 2001 funstuff/
-rwxr-xr-x 2 rmolnar staff 312 Oct 11 2000 new.html
Permissions
Owner
Group
Size
Date
Name
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Unix Permissions
Permission sequence found at the beginning ofa directory listing (first 10 characters):
d rwx r-x r-x
Directory
?
Owners
Permissions
Groups
Permissions
Worlds
Permissions
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Unix Permissions
The first character represents whether thelisting is a directory. If it is a directory, a d will
appear in the first character; otherwise, youshould normally see a dash (-).
d rwx r-x r-x
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Unix Permissions
The remaining nine characters are divided intothree triplets, each representing thepermissions for the owner, the owners group
and the world.
- rwx r-x r-x
Owner
Group
World
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Unix Permissions
In each triplet, three permissions can beassigned: 1st Position: r stands for Read; grants permission
to view the contents of a file or directory (Value is ror -)
2nd Position: w stands for Write; grants permission
to modify a file or the contents of a directory (Valueis w or -)
3rd Position: x stands for eXecute; grants permissionto run an application or open a directory (Value is xor -)
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Unix Permissions
When changing permissions, we must first decide whatnumber will represent the permissions for a triplet
We can do this by determining whether or not apermission is turned on or off If a permission is turned on (represented by r, w, or x), it gets
a value of 1
If a permission is turned off (represented by a dash), it gets a
value of 0 After deciding whether the three permissions in a triplet
are on or off, we will have a binary number
We can convert the binary number to its octalequivalent
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Unix Permissions
Permissions Binary Octal
- - - 0 0 0 0
- - x 0 0 1 1
- w - 0 1 0 2
- w x 0 1 1 3
r - - 1 0 0 4r x 1 0 1 5
r w - 1 1 0 6
r w x 1 1 1 7
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Unix Permissions
Once youve established the octal number representingthe permission for each triplet, you can then use the
change mode (chmod) command to give a directory orfile proper permissions
Syntax:chmod permissionMask file/directory
Example:chmod 755 public_html
Typically, directories and executable files are given755 permissions, while other files are given 644permissions
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Navigating Unix
To move from directory todirectory, we use the cd
command Syntax:
cd path/
To move from a parent to achild directory:
cd child/ To move from a parent to a
grandchild directory:cd child/grandchild
Grandchild Directory
Child Directory
Parent Directory
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Navigating Unix
To move from a child toa parent directory:
cd .. To move from a
grandchild to a parentdirectory:cd ../..
To move to a directorythat shares the sameparent:cd ../Child 2
Grandchild Directory
Child Directory
Parent Directory
Child 1 Directory Child 2 Directory
Parent Directory
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The List Command
The list command (ls) shows the contents of adirectory
We can add switches to the list command to modifywhat the command can do: ls lshows files in long format, including permissions (On
Phoenix, you can also use the aliasll)
ls ashows hidden files
lscshows file listings in a column format
ls tsorts file listings by last modified date
To use more than one flag, concatenate them:ls -lt
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Using Wildcards with ls
ls a* - Wildcard, All files starting with 'a'
ls *a* - All filenames with 'a' in them
ls *a*html - All filenames with 'a' in them and
ending with html
ls ????? - All 5 charater filenames
ls [abc]*- All filenames starting with a, b, or c
ls [a-c]* - Same as above but done as a range
ls [^a-c]* - All filenames not starting with a, b, or c
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The Unix Copy Command
cp can be used to make a copy of a file,
leaving the original file untouched
Syntax:cp oldfile [path/]newfile
To make a copy of a file while both the original
and copy are in the samedirectory:cp index.html home.html
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The Unix Copy Command
To make a copy of a file that results in the copyretaining the originals name, but is housed in adifferent directory:cp index.html ../academic/
To make a copy of a file that results in the copy
having a new nameand is housed in a differentdirectory:cp index.html ../academic/home.html
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The Unix Move Command
Themv command has two purposes:
To move files from one directory to another
To rename files
Syntax:mv oldfile newpath/[newfilename]
To move a file from one directory to another:mv index.html ../friends/
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The Unix Move Command
To rename a file (stays in the same directory):mv index.html home.html
To move a file andrename it at the same time:mv index.html ../friends/home.html
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Deleting Files
Use rmto delete files
Syntax:rm filename
To delete a single file:rm index.html
(answer Y to confirm delete)
To delete multiple files using a wildcard:rm *.html(answer Y to confirm delete for each file)
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Deleting Directories
Use rmdir to delete directories
DIRECTORY MUST BE EMPTY!!!!
Syntax:rmdir directoryname
To delete a directory:
rmdir images/(answer Y to confirm delete)
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Other Useful Commands
passwd Password utility that allows users toupdate their passwords
exit End your Unix session (you can alsousebye on Phoenix)
clear Gives you a blank screen (you canalso use cls on Phoenix)
who Lists users currently logged in to theserver
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Other Useful Commands
finger username Retrieves informationabout a user
cal Displays a calendar of the currentmonth
date Displays the current system date
!! (pronounced bang bang) repeats thelast command
![a..z] Repeats the last commandbeginning with selected letter (a-z)
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Other Useful Commands
|more Added to commands which displaylists to force page stops (Ex: ls lt |more)
C-z Temporarily stop a process
fg Bring a process to the foreground after ithas been stopped
vacation Turn on the autoreply for e-mailpine Launch the Pine E-mail client
emacs Start the Emacs editor
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Online Manual
Eight Sections Commands
System calls
Library functions
Devices and device drivers
File formats
Games
Miscellaneous
System maintenance
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Usingman
man command
To lookup help on the cp command:man cp
To lookup help on the ls command:man ls
C-c exits the manual.
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Questions?