9    System V Functionality

9.1    Overview

Digital UNIX Version 4.0 supports the following two System V packages in an effort to provide users, programmers, and administrators with complete System V Release 4 functionality:

• The System V Compatibility habitat

• The System V Environment

9.1.1    System V Compatibility Habitat

The System V Compatibility habitat ships with the base system and, in conjunction with the work done to extend the Digital UNIX Version 4.0 libraries to contain System V functionality, allows Digital UNIX Version 4.0 to conform to the following two volumes from the four volumes listed in the System V Interface Definition 3 (SVID 3):

• Volume 1: Base System and Kernel

• Volume 4: X11 Windows

  Note that NeWS Windows is not supported.

The System V Compatibility habitat consists of several commands in the /usr/opt/s5 directory (commands that are commonly used in shell scripts and that format their data differently from the corresponding Digital UNIX commands) as well as a separate System V shared and static library (libsys5.a and libsys5.so) that contains functions that are different from those already in the standard libc. For the most part, however, Digital has attempted to extend the functions and system calls in libc to include the necessary System V functionality and behavior so that many programs written for System V can compile and run on Digital UNIX Version 4.0 without the need to link against libsys5.

Also, Digital has added the swapctl and memcntl System V system calls to libc as well as support for the System V pseudodevice, /dev/zero, the /proc file system, the FDFS file system, SVR4 signals, and SVR4 STREAMS.

Users and programmers can access the Digital UNIX Version 4.0 System V Compatibility habitat either by placing the /usr/opt/s5 path in their .profile file or by using the absolute pathname for this directory. The cc and ld commands in the /usr/opt/s5 directory for example, are in fact shell wrappers which, when called, search the libsys5.a and libsys5.so libraries before looking in libc, so that programmers can access these libraries transparently.

For more information on the System V Compatibility habitat, see the System Administration guide , Programmer's Guide, and the Command and Shell User's Guide.

9.1.2    The System V Environment

The System V Environment extends the functionality provided by the System V Compatibility habitat by supporting a more complete System V Release 4 (SVR4) environment for general users, application programmers, and system administrators. The System V Environment is an extension to the operating system that contains a separate System V Release 4.0 binary license from UNIX Software Laboratories and requires a special license and a Product Authorization Key (PAK) to access.

The System V Environment extends the base system SVID 3 compliance to provide complete compliance to the SVID 3 standard, by supporting the following two additional SVID 3 volumes:

• Volume 2: Utilities and Administration

• Volume 3: Software Development, Terminal Interface, Realtime and Memory Management, Remote Services

See Figure 9-1 for a summary of SVID support in both Digital UNIX and the System V Environment.

Figure 9-1: SVID Compliance in the System V Environment

In addition, the System V Environment meets operating system requirements critical to the telecommunications industry, as defined in the Bellcore Standard Operating Environment (SOE), Issue 2.

The System V Environment supports the following functionality:

• Development tools and libraries

• Extended Terminal Interface

• Software management utilities ( pkg* commands)

• System administration commands and utilities, including backup and restore services

• User account management

• System activity reporting (sar)

• SVR4 Bourne Shell
  

• SVR4 printing subsystem

• Service access facility

• Realtime extensions

The System V Environment delivers the complete suite of SVR4 commands as well as the libsvr4 library, which contains all the SVR4 routines for the base system. Essentially, the System V Environment extends the functionality of the System V Compatibility habitat, allowing users, programmers, and administrators to work in a completely native System V environment, without the Digital UNIX "look and feel." However, through manipulating each user's .profile file, each environment, System V and Digital UNIX , can be accessed without difficulty and, with the exception of the Printing Subsystem, without reconfiguring the system. Note that programmers can develop and run both Digital UNIX and SVR4 applications simultaneously, no matter which environment they choose to adopt. For more information on the System V Environment, see the System V Environment for Digital UNIX Version 4.0 User's Guide and the SVR4 to SVE for Digital UNIX Version 4.0 Migration Guide.