Transcript 1. Introduction to Linux

Overview of PC Operating System
LI Xiang
Telecommunication Division, NMC, China
E-mail: [email protected]
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An operating system is the
software that provides the
interface between the hardware of
a computer system and the
applications programs that are
used on it.
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1. Introduction to Windows
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Windows is a series of operating systems developed by
Microsoft.
Object oriented and easy-to-use Graphical User Interface (GUI)
Multitasking Operating systems
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Multiprocessing
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allowing multiple processors to be utilized.
Multithreading
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allowing multiple software processes to be run at the same time.
allowing different parts of a software program to run concurrently.
Abundant in development tools and applications
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Visual Basic, Visual C, Visual FoxPro, Delphi, Power Builder, …….
Microsoft Office, Microsoft Visio, Internet Explorer,……
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MS Windows kernal
• Windows 9X kernal
• Windows 3.X/95/98/ME
• In 2001, Microsoft announced ceasing
the development of Windows 9X kernal.
• Windows NT kernal
• Windows NT/2000/XP
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Architecture of Windows 2000/XP
Non OS service process,
eg. WINLOGON, SMSS
System
support
process
OS service process, eg.
Event log service
Service
process
User
application
OS function call
interface
Environment
subsystem
Converting
public calling
interfaces to
internal
system calls
Subsystem DLLs
user mode
kernel mode
Executive
kernel
Device Drivers
GUI
Hardware Abstraction Layer
Scheduling threads
• Scheduling interrupt
• Synchronizing multiprocessor
-Memory management
-Process and threads
management
- I/O
•
Including the drivers of file
system and hardware
-Process communication
Major components of Windows
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Windows Desktop
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Control pannel
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Icons, Start Button, Taskbar
Configuration and management hardware
Configuration and management system resources
Install and uninstall application software
File manager
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Files and folders
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program files: executable
data files: not executable and associated with a specific program or file format
file naming
a file name can contain up to 255 characters including letters, numbers, spaces
and some other printable characters.
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a file name can’t contain the following characters:
/\:*?"<>|
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Tasks manager
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Displaying the status of processes current running on system
Stopping a process
Network
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Supporting NetBEUI, TCP/IP, IPX, ……
Providing the network application programs and tools, such as ftp, telnet, ping, tracert,
netstat,……
Allowing sharing disks, files and printers among MS Windows machines.
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2. Introduction to Unix
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Developed at Bell Laboratories in 1969.
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Written with the high-level programming language C.
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Initially designed for medium-sized minicomputers, and then
moved to mainframe computers and personal computers.
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For different hardware platforms, there are many different Unix
versions.
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AIX, Digital Unix, Hp Unix, ……
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Sco Unix, which is a PC-based Unix operating system
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Features of Unix
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Mature and stable operating system
Graphical User Interface operating system
Multitasking capability
Multiprocessing
Multithreading
Multiuser capability
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System portability
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allowing multiple users to utilize the computer and run
programs at the same time.
Capable of moving from one brand of computer to another
with a minimum of code changes .
The operating system could be upgraded without having all
the user's data inputted again.
Containing many tools and applications
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Unix functionally organized at three levels
offering additional
functionality to the
operating system
Tools and applications
shell
kernel
- Surrounding the kernel and acting as a user
interface to the Unix operating system
- Command language interpreter
- Interprets the command users enter
- Selects and runs the command or program
- Provides the results to the screen or file as
directed by the command
-C shell, Bourne shell, Korn shell
The main part of operating system, and
responsible for controlling system resources.
-Loaded into memory when the system
boots
-Process control and scheduling
-Memory management
-Device I/O
-System error handling
-User programs requesting services from
the kernel through system calls
-Hardware devices getting kernel response
through interrupts
User interface
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Providing two methods for user to
interact with the operating system
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GUI, for users of workstations or
intelligent terminals with bit-mapped
displays.
Command line interface, for users of a
character cell terminal or terminal
emulator.
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File system
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A hierarchical file system
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a root filesystem: /bin, /lib, /etc, /dev,……
a /usr filesystem: programs and unchanging data
a /var filesystem: changing data (such as log files)
a /home filesystem: user’s files
Types of files
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Ordinary disk files
Special files
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Directory flies
Naming files and directories
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Each physical device on a Unix system is treated as a special file.
Located in the /dev directory.
File and directory names can include letters, numbers, periods(.), underscores(_),
and some other printable characters.
Avoid characters with special programming or system meanings, such as /,
*?[]<>$’”&!.
Generally, a name of file and directory can contain up to 255 characters.
Accessing directories and files
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Accessing directories: cd , ls, pwd
Finding files: find
Viewing files: more, cat, tail, head
Editing files: vi, ed
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Controlling Processes (1)
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A process
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Is a program that is currently executing
Can be created and destroyed
Has resources allocated to it
Has an environment associated with it that:
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Process and process group IDs
Open files
Working directory
File creation mask
Real and effective user and group IDs
Resource limits: maximum file size, maximum amount of memory
Signal action settings
A set of named variables
Can create other processes
Can communicate with other processes
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Controlling Processes (2)
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Creating a process
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Running jobs in the foreground: command
Running jobs in the background: command &
Obtaining process status
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jobs
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ps
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Displays status of jobs in the current session
Job number, job status, PID
Shows current status of processes
PID, state, accumulated execution time, command, ……
Controlling and managing jobs
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Placing a job in the foreground: fg
Restarting a job in the background: bg
Stopping a process: Ctrl/C, kill
Setting process priority: nice
Scheduling jobs to run at appropriate times: at, crontab
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Networking Services
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UUCP
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TCP/IP
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Allowing transparent file access over TCP/IP networks among computers,
including Unix, Linux and MS Windows machines.
IPX/SPX
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rlogin, rcp, rsh, telnet, ftp
Ping, netstat, trouceroute
Network File System (NFS)
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Unix to Unix copy program
A batch-processing/spooling system
Typically used between systems with dial-up telephone lines or direct serial lines
Netware clients can log in Unix servers via Novell network.
LAN Manager Client
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allowing the sharing of files with MS Windows machines (via Network
Neighbourhood).
allowing the sharing of printers across machines.
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Online documentation
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Unix commands are documented on
line in the man pages.
The man command provides online
access to the system's reference pages.
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3. Introduction to Linux
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A free Unix-type operating system originally created by Linus
Torvalds with the assistance of developers around the world.
The source code for Linux is freely available to everyone.
GUI operating system, including many of the tools that
Windows users are familiar with such as,
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A file manager
A Window manager
A help system
A configuration
…….
Requiring less system resources. A Linux based system can
operate smoothly on a 386 or 486.
Application software support
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Office applications: Corel WordPerfect Office 2000 for Linux
Deluxe
Graphics tool: Gimp
Browsers: Netscape Communicator 4.75, Opera browser
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Examples
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PCVSAT, DVB, DAB
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CMA’s domestic communication system
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MS Windows
NICC: AIX
RICC, PICC: AIX, Digital Unix
CIMS: Sco Unix, will be replaced by Linux in future.
CMA’s GTS system
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VMS, will be replaced by UNIX in next year
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FTP
FTP
TCP
(get)
(put)
scokets
Data management PCVSAT Mux
and storage
- PC
- IBM H50
- Windows NT
- AIX
- Sybase
NICC
PCVSAT receiver Data
Database
management
- PC
- PC
- PC
- Windows 98
- Sco Unix
- Sco Unix
- Sybase
CIMS
Thank you
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