UNIX SVR4

COSC513

Zhaohui Chen

Jiefei Huang

UNIX SVR4

• UNIX system V release 4 is a major new release of the UNIX operating system, developed by AT&T and Sun microsystems

• Goals : standardization of the UNIX system and introduction of new technology

Standardization of the UNIX system

• Previous operating systems are open systems.• SVR4 is developed to provide a uniform

platform for commercial• It combines features from SVR3 , BSD4.3 ,

SunOS and Microsoft XENIX system V.

Introduction of new technology

• Extends networking capabilities

• Improves system administration and maintenance

• Further internationalizes the UNIX system

SVR4 new features

• Operating system enhancements

• File system enhancements

• Networking

• System administration and maintenance

• Real-time support

SVR4 new features

• Character user interface

• Graphical user interface

• Internationalization

• C language

• Extended terminal interface

Operating system enhancements

SVR4 uses a virtual memory architecture based on SunOS which has efficient use of system’s main memory and capability to execute very large programs.

Additional benefits

Mapped files : allows a file to be mapped explicitly into the address

space of a user program. This makes user program easier to write and allows programs to execute more efficiently.

File system enhancements

Virtual file system : allows several

different file system types to coexist

on the same system.

rfs (BSD based)

nfs (SunOS based)

s5 (earlier UNIX release based)

System administration and maintenance

• Software installation and configuration management tools : allows an administrator easy access to information

• System administration menus : allows a user to administer a UNIX system without knowledge of UNIX system commands.

Real-time processing

• User-controlled process scheduler : kernel code that determines what program will run, when, and for how long.

• High-resolution timers : gives microsecond resolution, good for applications deal with very short time intervals.

Character-based user interface

• Framed access command environment : an interface allows a user to see the UNIX system through frames containing menus and forms.

• SVR4 enhanced FACE to be more consistent and adding applications to FACE has been made easier.

Graphical user interface

• OPEN LOOK graphical user interface : defines a standard for the ‘look and feel’ of the GUI applications.

• XWIN graphical windowing system : gives the user the ability to create multiple windows on a single display,with each window running different applications.

Internationalization

• Support for multiple international code sets and character

• Translate system messages to the user’s native language

• Support the national conventions used to communicate

C language

• Enhanced c packages : C programming language utilities(CPLU), Advanced programming utilities(APU), C programmer productivity tools(CPPT).

• New features : dynamic linking dynamic tables . . .

Extended terminal interface

• Standard programming interface provided in release 4 for character screen management and character operations.

• Consists of 3 libraries

• Provides C subroutines for creating forms , menus, form editing functions,panels

Networking on UNIX SVR4

• UNIX SVR4 merges the networking facilities of UNIX SVR3, BSD4.2 and 4.3, and SunOS.

• It also introduces new networking routines .

Networking on UNIX SVR4

From UNIX SVR3

• Transport level interface (TLI)

• Remote file sharing mechanism(RFS)

• Streams

From BSD 4.2 and 4.3

• TCP/IP protocols

• Sockets

• Inetd facility

From SunOS

• Network file system (NFS)

New facilities in SVR4

• The network selection mechanism

• Name-to-address mapping

Transport level interface (TLI)

TLI defines an interface between applications and transport level network protocols, relieving user programs of the need to know the protocol characteristics.

Remote file sharing (RFS)

It provides transparent access to remote files and devices .

Stream

• A framework for developing network protocols

• It defines standard interfaces that allow networking architectures and high-level protocols to be independent of underlying protocols,drivers,and media.

TCP/IP

UNIX system V release 4 supports TCP/IP and supports networking among systems of different types.

Sockets

• Sockets is a networking interface widely used in BSD systems which defines how a process accesses the services of a protocol.

• In SVR4, sockets is provided in a library so that BSD applications that use sockets can migrate easily to SVR4.

Inted

• In release 4 , UNIX system V supports inetd, a port monitor that waits for service requests from computers on a TCP/IP network.

• When a connection request arrives, inted spawns the server process and passes the network connection to it.

Network file system (NFS)

• A standard for sharing files between different machines, operating systems in a network

• Users can get directly to the files they want without knowing the network address of the date.

Network selection

• New features in UNIX SVR4

• it allows network applications to choose the network over which they will communicate.

• If an application fails to connect with its first choice, it can select different networks until it finds one that meets its requirements and allows the connection.

Network selection

With Network selection, an application does not need a network selection embedded in its code. This allows the application to run without modification on different systems that support different networks.

Name-to-address mapping

Name-to-address mapping is a mechanism that allows network clients to determine the addresses of servers on a network in a network independent manner.

Name-to-address mapping

• This mechanism makes it possible for clients to reach a server, even if the address on which the server is listening should change.

• It also allows a client to reach a server over different networks.

References

• AT&T,UNIX SYSTEM V/386 RELEASE 4 product overview and master index, Unix press 1991

• Michael Padovana, Networking applications on UNIX system V release 4, Prentice Hall 1993

• M Santifaller, TCP/IP and NFS:internetworking in a UNIX environment,Addison-Wesley 1994

• Mark G Sobell,Unix system V:a practical guide, Addison-Wesley 1995

• http://www.stokely.com/unix.sysam.resources/index.html

• http://darkwing.uoregon.edu/~hak/unix.html