What is UNIX

The Single UNIX® Specification, Version 2 and UNIX 98

A Technical White Paper from the Open Group.

Version 1.3 Last update January 3rd 1998.

Available as a PDF file


Developed through the X/Open consensus process the Single UNIX Specification Version 2 and the UNIX 98 Product Standards introduce the next generation of 64-bit enabled UNIX system architectures, and reinforce the UNIX trade mark as the industry recognized mark for the leading-edge operating environment.

This delivers to the market the benefits of a single standard operating system, namely application and information portability, scalability, flexibility and freedom of choice for customers.

Continuing its commitment to Open Systems, The Open Group is pleased to announce availability of the Single UNIX Specification, Version 2 on the World Wide Web at URL http://www.UNIX-systems.org/go/unix.

Version 2 of the Single UNIX Specification builds upon the original and updates it with the latest formal standards and the latest industry practises. In particular it introduces the following functionality into the core definitions:

For those of us who count interfaces, the Single UNIX Specification Version 2 now has over 1400 programming interfaces. The UNIX 98 Workstation profile which includes CDE (and thus X11 and Motif) increases this number to over 3000 programming interfaces.

What is UNIX 98 ?

UNIX 98 is the mark (or label) for systems conforming to Version 2 of the Single UNIX Specification.

UNIX 98 is

If a product is registered as conformant to UNIX 98 the vendor warrants and represents that it:

UNIX 98 is organized as a family of product standards addressing different market needs.

The following diagram shows the internet services included in the UNIX 98 Server product standard:


Benefits for Application Developers

Benefits for Users

UNIX 98 Standards Feature Matrix

 Feature  UNIX 95  UNIX 98  UNIX 98 WorkStation  UNIX 98 Server
 System Software
 POSIX.1  X  X  X  X
 POSIX.2  X  X  X  X
 POSIX.1b    X*  X*  X*
 POSIX.1c    X  X  X
 FIPS 151-2  X  X  X  X
 FIPS 189  X  X  X  X
 ISO C  X  X  X  X
 ISO C Amendment 1    X  X  X
 XSockets  X  X  X  X
 XTI  X  X  X  X
 X/Open Threads Extension    X  X  X
 Y2K Changes    X  X  X
 Dynamic Linking    X  X  X
 Large File Support    X  X  X
 Data Size Neutral    X  X  X
 User Interface
 CDE      X  
 Motif      X  
 X11 Window Server      X  
 Internet Standards
 Java Runtime Environment 1.1        X
 Java Class Libraries 1.1        X
 TCP/IP IPv4        X
 HTTP 1.1 Server        X
 SSL V3 Server        X
 DNS Server        X
 Secure DNS Server Extensions        X
 Telnet Server        X
 Ftp Server        X
 NFS Server        X
 WebNFS Server        O
 POP3 Server        X
 IMAP4 Server        X
 SMTP Server        X
 LPD Server        X
 NTP Server        X
 LDAP V2 Server        X
 LDAP V3 Server        O
 SNMP Agent        X
 DHCP Server        X
 TFTP Server        X
 BOOTP Server        X


*=Realtime Feature Group

UNIX vs POSIX Feature Matrix

 Feature  FIPS 151-2  UNIX 95  UNIX 98
 1003.1-90 Processes  Multiple  Multiple  Multiple
 1003.1-90 Pipes  X  X  X
 1003.1-90 Files and Directories  X  X  X
 1003.1-90 Basic I/O  X  X  X
 1003.1-90 Async I/O  X  X  X
 1003.1-90 Signals  X  X  X
 1003.1-90 Users and Groups  X  X  X
 1003.1b-93 File Synchronization    X  X
 1003.1b-93 Memory Mapped Files    X  X
 1003.1b-93 Memory Protection    X  X
 1003.1b-93 Process Priority Scheduling      Realtime FG
 1003.1b-93 Memory Locking      Realtime FG
 1003.1b-93 Synchronized I/O      Realtime FG
 1003.1b-93 Asynchronized I/O      Realtime FG
 1003.1b-93 Hi Resolution Clocks & Timers      Realtime FG
 1003.1b-93 Realtime Signals      Realtime FG
 1003.1b-93 Semaphores      Realtime FG
 1003.1b-93 Shared Memory      Realtime FG
 1003.1b-93 IPC Message Passing      Realtime FG
 1003.1c-95 Threads      X
 1003.1c-95 Thread Safe Functions      X
 1003.1c-95 Thread Attribute Stack Address      X
 1003.1c-95 Thread Attribute Stack Size      X
 1003.1c-95 Thread Process Shared      X
 1003.1c-95 Thread Priority Scheduling      Realtime Threads FG
 1003.1c-95 Thread Priority Inheritence      Realtime Threads FG
 1003.1c-95 Thread Priority Protection      Realtime Threads FG
 1003.2/2a Shell & Utilities    X  X
 P1003.1g (DRAFT) Protocol Independent Interfaces      X

FG=Feature Group

New Test Suites for UNIX 98

Open Group test tools are essential for proper development and maintenance of standards-based products, ensuring conformance of products to industry-standard APIs, application portability and interoperability. In-depth testing identifies defects at the earliest possible point in the development cycle, saving costs in development and quality assurance. The real benefit of The Open group test tools to suppliers is accelerated time-to-market of branded product.

Several new test suites are being introduced with UNIX 98.

For more information on new developments in Open Group testing , see http://www.opengroup.org/testing/new.

More Information

More information on the Single UNIX Specification, Version 2 can be obtained from the following sources:

Copyright The Open Group, © 1997

UNIX is a registered trademark of The Open Group

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