.\"Trademarks:
.\"UNIX is a registered trademark of AT&T.
.\"XENIX is a registered trademark of Microsoft Corporation.
.\"NeWS and SunOS are registered trademarks of Sun Microsystems.
.\"OPEN LOOK and XWIN are trademarks of AT&T.
.\"Postscript is a registered trademark of Adobe Systems, Inc.
.\"VAX is a trademark of Digital Equipment Corporation.
.HW de-vice
.HW in-stal-la-tion
.if n .pH po.chap1 @(#)chap1	40.18
.\" Copyright 1989 AT&T
.BK "Product Overview and Master Index"
.CH "Product Overview" 1
.H 1 "About This Manual"
This volume is intended to be a starting point for exploring
UNIX\(rg System V and a central reference when using the
UNIX System V Release 4.0 documentation.  It includes a 
product overview, which
introduces a new user to the UNIX system in general and specifically
to Release 4.0.  More important, it includes a master index, 
which indexes all the documents in the UNIX System V 
Release 4.0 document set.
.P
The UNIX system is a vast, continually evolving system, and it is not
possible to provide a new user with a complete description of
the system in a few pages.  The product overview 
in this volume is merely an
introduction to the system, including a description of the
software and documentation that make up the UNIX System V 
Release 4.0 product;
you are directed to other documents for detailed descriptions
of features, as well as user instructions.
The overview does not assume prior knowledge of the UNIX 
system or of earlier
releases of UNIX System V.  If you are upgrading from an earlier
release of UNIX System V, you should see the \f2Migration Guide\f1 for a
description of Release 4.0 that explains the differences between
the new release and previous releases.
.H 1 "Introduction to the UNIX Operating System"
UNIX System V is an interactive, multi-user, multi-tasking
operating system.
An 
.I "operating system" 
is a set of instructions that governs how 
the electronic components of your computer interpret and respond to 
commands and to coded instructions in your application software.
Because UNIX System V is an
.I interactive 
system,
you enter commands from 
your keyboard, and the system responds
by executing your command or by prompting you for additional input.
Because it is a 
.I multi-user 
system, many people can use the system at the same time, 
working together, sharing information, and
using common tools.
Because the system is 
\f2multi-tasking\f1,
it can perform several tasks for you at the same time,
executing one task, or 
\f2process\f1, in the background while you move
on to another task.	
.H 2 "A Brief History"
Originally developed at Bell Laboratories in the 1960s,
the UNIX system was designed to serve the research 
community\(emspecifically researchers working together on a common
project, each with a vital need to share information and with a
need to construct programs quickly and easily to 
perform specialized functions.
.P
Prior to the 1980s, the UNIX system was
used primarily in university and government research centers.
Built around a set of small but powerful tools, the UNIX system 
soon proved to be well suited to the development of
computer software and easily tailored to specific industry
applications. 
.P
Because of AT&T's liberal licensing of the 
UNIX system, different versions of the system began to appear in
the early 1970s.  Universities as well as equipment vendors 
obtained licenses to use
the system, then modified it to meet their special needs.  
The first commercial implementation of the system
appeared in the mid-1970s, followed soon afterward by
the introduction of Microsoft Corporation's UNIX system
product\(emthe XENIX\(rg operating system.
.P
In 1981, the University of California at Berkeley introduced an 
implementation, called Berkeley
Software Distribution (BSD), that quickly became a standard on 
Digital Equipment 
Corporation's VAX\(tm line of computers.  From BSD, many other versions 
of the UNIX system evolved.
.P
By the early 1980s, the UNIX system was running in a wide 
range of environments on a wide variety of systems
from a number of different equipment 
manufacturers\(emmaking it unique in the computing
world.
.P
In 1984, following a court-ordered divestiture that removed
legal obstacles to its entry into the computer industry, AT&T 
began licensing the system commercially as UNIX System V.
.H 2 "The Structure of the UNIX System"
UNIX System V is a powerful operating system built upon a 
few simple concepts.  Typically, the UNIX system is described 
as consisting of three major parts.  These 
are 
.BL
.LI
the UNIX operating system kernel
.LI
the shell command interpreter and programming language
.LI
the file system.
.LE
.P
The following sections briefly describe these components
of the UNIX system.
.H 3 "The Kernel"
The UNIX system
.I kernel 
is the component of the operating system that
controls user processes 
(commands and programs) and 
manages system resources, such as the file system.
It interacts directly with the hardware, passing information
back and forth between the hardware and software programs. 
The kernel surrounds the hardware, insulating it and eliminating
the need for a program to be aware of machine architecture.
The fact that machine architecture is hidden makes it easier 
for software developers to write
programs that run on different hardware.
.P
The kernel manages the computer's processor so that processor time
is allocated among multiple users and applications.  Processor time
is scheduled such that programs seem to execute simultaneously.
.H 3 "The Shell"
The UNIX system
.I shell 
is a command interpreter that recognizes and interprets commands 
entered by the user from a keyboard.
While the shell is a simple interface for the novice user, it provides
the experienced user with a great deal of power and flexibility.
.P
The design of the shell makes it easy to manipulate files and the 
input and output of commands.  Commands can take their input from 
either a terminal or a file, and the output of commands can be 
directed to a file or to a peripheral device other than the terminal.
In addition, you can specify the output of one command 
as the input of another command\(eman action called
``piping.'' 
This capability allows users to build their 
own specialized functions easily.
.P
Using the shell as a programming language, the
user can write custom shell procedures to do simple 
or complex tasks, letting the shell handle details like
opening and closing files.
The shell allows users to enhance and build on
UNIX system capabilities and to adapt the operating system to many
user applications without using a compiler or link editor.
.P
For more information about the shell as both a user interface and
a programming language, see the UNIX System V Release 4.0
\f2User's Guide\f1.
.H 3 "The File System"
A \f2file system\f1 is a collection of directories and files 
where users organize and store data.
.P
A \f2file\f1 is a location where
you store data.  Typically, a file is
described as an
electronic equivalent of a paper document.
You give the file a name that identifies its contents, 
just as you would title a document.
.P
A \f2directory\f1 is where you organize related
files.  To continue the analogy, a directory is like
a file folder, where you store similar kinds of documents.
You give the directory a name that
describes the general contents of all your
files, just as you would label a file folder.
.P
To complete the analogy, a file system (in simplest
terms) is like a drawer of your file cabinet, which contains
multiple file folders that contain multiple documents.
.P
UNIX System V organizes files and directories
hierarchically in a tree-like structure that makes it easy for
users to locate and maintain their files.
It also provides facilities for creating, 
accessing, copying, moving and processing files, directories, or 
sets of these in a simple, 
consistent way.  Space for files is automatically allocated 
and deallocated
when a file is created or deleted and as it grows and shrinks in size.
This means you do not need to allocate space for a file before it is
used.
.P
The UNIX system supports multiple file systems and file systems of
various types, such as the traditional UNIX System V file system, which
stores data in blocks of 0.5K, 1K, or 2K bytes, and UFS, a file
system type that stores data in blocks as large as 8K bytes.
File systems are ``mountable'' and ``unmountable,'' which means that 
file systems can be stored on removable media and made 
available to a user or group only when needed.
This gives users easy
access to additional disk space.
.P
The UNIX system treats all files 
identically because it hides the differences between file types.
This is what makes it possible to use the output of one program 
as the input to another program.
.H 2 "Benefits of the UNIX System"
What
makes the UNIX system unique among operating systems is its power
and flexibility\(emqualities that recall its origins in the
research community.  
The design elements that make the UNIX system such a powerful
yet flexible system also make it a highly 
portable one, which means that the UNIX system is
compatible with a wide range of hardware and software products.
.H 3 "Power and Flexibility"
The power and flexibility of the UNIX system are seen in its
multi-user, multi-tasking capabilities.
The multi-user capability allows you to work independently
on the system while sharing resources and data easily
with other users.
The multi-tasking capability means that you can 
execute commands and run programs simultaneously, using
several different methods.  In addition to normal
interactive mode, jobs can be submitted to run in the
``background.''  While one job is executing this way, you
can use the terminal interactively on another job.  If
you need to run several sessions interactively on the
same terminal, you can do so, using commands such as 
\f4shl\f1.
.P
The UNIX system's power and flexibility can be seen in 
features that encourage productivity
(such as pattern-matching capabilities and 
the ability to execute a command on many files at once)
and in its
versatile command set.  The system provides utilities
for retrieving information, manipulating data, generating
reports, and editing batch files.  It also provides
programs that identify a set of files based on their file
system attributes.
.P
The system's power and flexibility are also seen in
a rich collection of programming tools\(emtools
important not only to programmers but to \f2all\f1 users
who need to construct quick solutions to specialized problems.
The shell, for example, is more than an interface.
It's a mechanism that lets
you build powerful functions out of existing, simpler
functions by chaining commands together and using the
output of one command as the input for another.
.P
The flexibility of the UNIX system is well-known
to software developers.
UNIX System V is designed so that applications, as well as
new devices and protocols, can be added easily, without
modifying the source code.
The availability of various commands, languages, and libraries
of programs makes it easy to develop and maintain new application 
or system programs.  
.H 3 "Portability"
The UNIX system is a highly portable operating system, which means
that it is easily modified to run on a wide range of hardware
with a minimum of differences across implementations; 
once a user learns the UNIX system, he or she can use the system
on different hardware without having to \f2re\f1learn.
In addition, the structure of the kernel makes it possible to design
application software with no knowledge of the underlying machine
architecture, so that applications can run on a wide
variety of hardware installations.
.P
UNIX System V provides programmers with
tools that support the development
of portable applications, such as the \f4curses\f1 library 
and the \f4terminfo\f1
database.  These tools allow user programs to produce output on 
many different types of terminals; applications can be 
terminal-independent but still use terminal-dependent 
specifications stored in a common database.
.P
The portability of the
UNIX system and the resulting compatibility between implementations
on different manufacturers' equipment have contributed to 
the acceptance of the UNIX system as a 
.I "de facto" 
standard in the industry for portable operating systems.  
To preserve the UNIX system as a 
.I "de facto" 
standard, AT&T is committed to standardizing the system and 
unifying the various versions distributed by different equipment
vendors into a single, 
common base system.  Toward that goal, AT&T publishes the 
\f2System V Interface Definition\f1 (SVID), a set of documents 
that defines 
the minimum functionality a UNIX system product must deliver to 
be called UNIX System V.
AT&T also provides the System V Verification Suite (SVVS) Release
4.0, a set
of tests vendors can run against their UNIX system products to
confirm that they conform to the SVID specifications.
.P
In addition to defining its own standards, AT&T participates in
the efforts of industry standards bodies, such as the IEEE.
For more information about AT&T's standardization and unification
efforts, see
``Introduction to Release 4.0'' later in this guide.
.H 2 "Recommended Reading"
It is impossible to give more than a cursory overview of
UNIX System V in these few pages.  Throughout this overview,
you will be referred to guides and manuals in the UNIX 
System V documentation set
for more information on specific topics.  A description of
the entire set of documents available with UNIX System V appears
in ``Product Description'' later in this
overview.
.P
In addition to the UNIX System V documentation set, 
the following mass market books
provide the beginner with an introduction to the
UNIX system:
.BL
.LI
\f2The UNIX for Beginners Book: A Step-by-Step Introduction\f1, by Bryan
Strong and Jay Hosler.  New York: John Wiley & Sons, 1987.
.LI
\f2Introducing UNIX System V\f1, by Rachel Morgan and Henry
McGilton.  New York: McGraw-Hill, 1987.
.LE
.H 1 "Introduction to Release 4.0"
UNIX System V Release 4.0
is a major new release of the UNIX operating
system, providing a wealth of new features 
and enhancements to the system.  These features and
enhancements are designed and implemented as part of
AT&T's continuing commitment to the following goals:
.BL
.LI
Standardization of the UNIX system and the unification
of UNIX system derivatives.
.LI
Introduction of new technology\(emspecifically, new technology that
extends networking capabilities, improves system
administration and maintenance,
and further internationalizes the UNIX system.
.LE
.P
The following sections describe the features 
of Release 4.0 in terms of these goals.
Throughout the discussions, you are referred to
other documentation for feature information 
that goes beyond the scope of this product overview.
.H 2 "Standardization and Unification"
UNIX System V is an
.I "open"
operating system.  As an open system, manufacturers
of computing equipment can license rights to use it
and customize it to
meet the specific needs of their markets and product lines.
As a result of the open licensing, many versions of the system
have diverged to the
point where customers may be confused as to what the
UNIX system is today.
Release 4.0 represents a major step in AT&T's efforts 
to standardize the UNIX system and to unify the various UNIX system 
derivatives into a single, common base.
.P
The goal of Release 4.0 is to merge the best of the UNIX
systems based on Berkeley Software 
Distribution (BSD), such as SunOS\(rg, with the 
best of UNIX System V, provide XENIX system compatibility, 
and conform to the standards set by the IEEE POSIX committee.
To encourage 
continued progress toward a UNIX system industry standard, 
Release 4.0 has been released in conjunction with the
System V Interface Definition, Third Edition (SVID3).
.H 3 "BSD Convergence"
In an effort to converge on one standard UNIX system, AT&T is 
working to resolve differences between
BSD-based versions of the UNIX operating system 
and UNIX System V.  Toward that end, Release 4.0 provides 
.BL
.LI
a library that implements the BSD sockets interface
.LI
4.3 BSD signal mechanisms
.LI
BSD commands, integrated into the UNIX System V command set
.LI
BSD Job Control
.LI
the TCP/IP network protocols (the DARPA Internet Protocol Suite)
.LI
Remote Procedure Call (RPC) and External Data Representation
(XDR) libraries
.LI
The Network File System file-sharing utility (Sun Microsystem's 
file distribution product, based on BSD)
.LI
Virtual File System (VFS) Architecture\(eman architecture that merges
AT&T's File System Switch and Sun Microsystem's Vnodes and
provides a mechanism that allows multiple 
file system types to coexist within UNIX System V;
VFS also incorporates BSD functionality and
symbolic links
.LI
UFS, an alternative file system type 
based on 4.2 Berkeley Fast File system
.LI
Multiple groups and ownership changes.
.LE
.P
For more information about BSD features, 
see ``Release 4.0 Features'' later in this guide.
.H 3 "XENIX System Compatibility"
UNIX System V provides full source code compatibility
with Microsoft's XENIX system.
XENIX system features first supported in AT&T's implementation of
UNIX System V Release 3.2 for the 386 processor are supported
in the source code in Release 4.0, along with
XENIX system file and record locking
(via the \f4locking\f1 function), shared memory, and semaphores. 
Existing XENIX system source code that uses these facilities compiles
and runs in Release 4.0.
(These facilities are provided
strictly for compatibility with existing XENIX system source code.  New 
applications should use SVID interfaces.)
.P
For more information about XENIX system compatibility, see the 
\f2BSD/XENIX\(rg Compatibility Guide\f1.
.H 3 "POSIX Conformance"
With Release 4.0, AT&T continues its commitment to
the Institute of Electrical and Electronics Engineers (IEEE)
standards efforts.
The IEEE P1003 standards committee
recently published a standard for the UNIX operating system,
known as POSIX (Portable Operating System Interface for Computer Environments).
While the POSIX specification is close to AT&T's own standard 
definition as documented in SVID3,
Release 4.0 provides the few changes and additional features required
to bring UNIX System V into full conformance with the POSIX
standard.
.P
For more information on POSIX conformance, see the
\f2Programmer's Guide: POSIX Conformance\f1.
.H 3 "Device-Kernel Interface/Device Driver Interface"
A goal of
Release 4.0 is to support popular interfaces to the UNIX
system and to provide new interfaces that are consistent with
industry standards. 
In Release 4.0, UNIX System V supports the 
Device-Kernel Interface (DKI), an
interface between the UNIX System V kernel and
device driver software.  DKI makes it easier to port
driver code across implementations of Release 4.0 for different
hardware; if the driver writer conforms
to the DKI where possible, the portability of the driver to other 
UNIX System V Release 4.0 implementations is greatly enhanced. 
.P
Release 4.0 also supports the Device Driver Interface (DDI), a 
superset of the DKI that is specific to the implementation of 
UNIX System V for the AT&T 3B2 line of computers.  The DDI
enhances driver binary 
compatibility across releases of UNIX System V for the
3B2 computers.
.P
See the \f2Device Driver Interface/Driver-Kernel Interface (DDI/DKI)
Reference Manual\f1 for more information.
.H 3 "SVID Publication"
The System V Interface Definition (SVID) is AT&T's 
published definition of interfaces to UNIX System V.  It 
defines the operating system program interfaces that
are consistent across all UNIX System V implementations,
and specifies an operating system environment that allows 
users to create application software that is independent 
of any particular computer hardware.
.P
The availability of Release 4.0 has been coordinated with the 
publication of
the System V Interface Definition, Third Edition (SVID3), 
which documents the functionality of 
Release 4.0 and presents
possible future directions for UNIX System V.
.H 2 "Release 4.0 Features"
Release 4.0 introduces a wealth of new features to UNIX System V, 
some of which were
introduced in BSD UNIX systems prior to the release
of UNIX System V Release 4.0.  These features are now supported in 
UNIX System V as part of AT&T's effort to unify the UNIX system 
derivatives into one standard product. 
.P
The new features introduced in Release 4.0, and the BSD features
that have been incorporated in UNIX System V, are described in
the following sections:
.BL
.LI
Operating System Enhancements
.LI
File System Enhancements
.LI
Networking
.LI
System Administration and Maintenance
.LI
Real-Time Support
.LI
Character User Interface
.LI
Graphical User Interface
.LI
Internationalization
.LI
C Language
.LI
Extended Terminal Interface
.LE
.H 3 "Operating System Enhancements"
As part of the effort to unify the various UNIX systems into
one standard, Release 4.0 introduces some fundamental
changes to UNIX System V.  These include 
the Virtual Memory (VM)
memory management architecture,
a system access mechanism called Service Access Facility,
STREAMS-based terminal subsystem and pipes,
BSD job control,
Expanded Fundamental 
Types,
and booting changes and enhancements.
.H 4 "Memory Management"
Release 4.0 incorporates a third-generation memory management 
architecture based on the VM (Virtual Memory) architecture 
introduced in SunOS.
VM replaces both the original UNIX system swapping 
architecture and the REGIONS demand-paged virtual memory 
architecture introduced in UNIX System V Release 2.
.P
The benefits of a demand-paged virtual memory implementation are 
efficient use of the system's main memory and the
capability to execute programs much larger than the physical memory
provided by the system.  The Release 4.0 VM architecture provides these 
same benefits, plus additional benefits of interest to 
particular groups of users (as indicated below in 
parentheses):
.SP
.BL
.SP
.LI
Mapped files (application programmers)
.P
A by-product of the VM architecture is a style of file
I/O for user programs called ``mapped files.''
This set of capabilities, provided by the \f4mmap\f1 family of routines,
allows a file to be mapped explicitly into the address space 
of a user program, 
where the file can be manipulated as if it were an array in 
primary memory.
These capabilities make
user programs easier to write, and they
allow programs to execute more efficiently.  For more
information, see the
\f2Programmer's Guide: System Services and Application 
Packaging Tools\f1.
.SP
.LI
Shared memory  (application programmers)
.P
The mapped files provided by VM can be considered a form 
of shared memory.
If several processes map a file simultaneously,
the system maps the same copy of a file into the memory space
of all processes.
.P
Release 4.0 also supports the
traditional UNIX System V shared memory facility (provided by 
the \f4shmat\f1 family of routines) 
and XENIX system shared memory 
semantics.
.SP
.LI
Flexible use of disk space for swapping (administrators)
.P
UNIX System V Release 4.0 swaps pages of data 
from main memory to an ordinary file on one of the system's disks.  
Swapping to a file accommodates the needs of diskless systems and 
allows for the more efficient use of disk space.
.SP
.LI
Portable implementation (porters)
.P
The VM architecture isolates all 
hardware-dependent portions
of the memory management subsystem in one block of C language
source code.  The remainder of the code is portable across
different hardware and system architectures.  Most of the 
hardware-dependent code 
comprises a well-defined Memory Management Unit (MMU) interface.  This 
interface allows the architecture to be implemented on top of different 
MMU hardware.  (This means that the Release 4.0
memory management subsystem is simple to port to other hardware,
because the hardware-dependent code is isolated
in one small part of the system
and has a simple interface.)
.P
Release 4.0 provides a ``multi-level store'' implementation of VM
that allows a system to address extremely large ranges of virtual 
address space using only a 32-bit hardware address space\(emthe 
industry standard for central processors and hardware memory management 
units.  
(This means that Release 4.0 is simple to port to standard
processor architectures.)
.LE
.P
For more information about VM, see the
\f2Programmer's Guide: System Services and Application Packaging Tools\f1.
.H 4 "Service Access Facility"
Service Access Facility (SAF) is a feature in Release 4.0 
that standardizes 
the way UNIX System V handles connection requests from outside the
system. The SAF acts as an umbrella over the system external 
access points 
and provides a consistent access mechanism.
Services are administered through a consistent framework 
of commands and files, whether they are requested from the 
console, from a terminal via a tty line, or across a network.
.P
For more information, see the \f2System Administrator's Guide\f1 
and the \f2Programmer's Guide: Networking Interfaces\f1.
.H 4 "STREAMS"
STREAMS is a mechanism that provides a framework for character 
I/O in the UNIX
system.  STREAMS allows programmers to structure kernel software in 
a modular manner and define standard interfaces within the kernel.
.P
STREAMS was introduced in an earlier release of UNIX System V as 
a mechanism for
implementing network protocols in a way that allows application
programmers to develop network applications that 
are protocol-independent.  In Release 4.0, the STREAMS mechanism
is more pervasive.  The terminal subsystem 
has been reimplemented using STREAMS, providing the 
following advantages:
.BL
.LI
A decrease in complexity of the kernel
.LI
Modularity and flexibility of code
.LI
Seamless integration of user terminals and networking
capabilities
.LI
Reusable line discipline modules
.LI
Customization
.LI
Ease in adding new features to the terminal subsystem.
.LE
For consistency, other mechanisms such as ``pipes'' have also 
been implemented using STREAMS
so that, in Release 4.0,
the entire character I/O subsystem is STREAMS-based.
.P
For more information about STREAMS, see the 
\f2Programmer's Guide: STREAMS\f1.
.H 4 "Job Control"
Job control is a popular feature of the BSD operating system and 
an optional part of the IEEE P1003.1 POSIX standard.  
Job control allows a user to 
stop and later resume a job, whether it is executing 
in the foreground or the background.  Job control also allows a 
user to move jobs back and forth between the background and 
the foreground.
.P
With job control a user can
.BL
.LI
stop a foreground job in order to perform a more 
pressing task
.LI
put a foreground job in the background
.LI
stop a job to satisfy a need of the job, such as 
looking up data for input or changing the name of an input 
file to match what was misspelled on the command line.
.LE
.P
Job control capabilities are available through an optional
shell called the job control shell (\f4jsh\f1).
For more information about job control, see the \f2User's Guide\f1.
.H 4 "Expanded Fundamental Types"
Release 4.0 supports the expansion in size
of certain data types, such as user ID (uid), process ID (pid), and 
device ID.  This feature, known as Expanded
Fundamental Types (EFT), makes it possible to remove 
constraints on certain 
.VS 2
.ne 10
.VE
fundamental system types that were 
imposed by the UNIX operating system's original hardware 
implementation.
.H 4 "File-System-Independent Booting and Autoconfiguration"
File-system-independent booting allows an administrator to boot 
the system from any device that is readable by firmware.
.P
In Release 4.0, it is possible to make the root file system 
either a standard UNIX System V file system or a UFS file system.
Rather than code knowledge of the
possible file system types into the boot program,
a disk partition is created 
when Release 4.0 is installed
that holds a file system of type \f4bfs\f1 (Boot File System).  This file 
system contains all the bootable programs necessary for the 
computer's boot process.
.P
In Release 4.0, the autoconfiguration process\(emthe process 
of detecting hardware 
and software changes on powerup or reboot and automatically 
generating a new bootable operating system\(emoperates
in the same file-system-independent 
manner as the boot program.
.H 3 "File System Enhancements"
Release 4.0 introduces a number of significant changes related
to file systems.
Most important, it introduces Virtual 
File System, 
an architecture that makes it possible for file systems of various types
to coexist on the same system; the traditional
UNIX System V file system type is now just 
one of many supported file system
types.  Also, the layout of the directory tree has been reorganized in 
Release 4.0 to facilitate sharing files, 
directories, and file systems in a networked environment.
.H 4 "Virtual File System"
Release 4.0 introduces to UNIX System V a file system switch architecture 
called Virtual File System (VFS).
VFS provides a clearly defined, 
modular interface between file systems and the rest of the UNIX 
system kernel, and allows several different file system types to 
coexist on the same system\(emincluding file systems that have
significantly different characteristics and internal formats.
The modular nature of the architecture allows programmers to design 
and install new file system types in a clean, straight-forward manner.  
.H 4 "New File System Types"
By reimplementing the UNIX System V file system architecture, 
Release 4.0 can support
a wide variety of file system types on the same system.
In addition to providing a mechanism that allows new types to be
defined and installed, 
Release 4.0 provides the following file system types as 
standard options.
.VL .8
.LI \f4s5\f1
the traditional file system type 
supported in earlier releases of UNIX System V.  The s5 type stores data 
in disk blocks of 0.5K, 1K, or 2K bytes.
.LI \f4ufs\f1
a file system type based on the BSD system ``fast file system'';
it supports data storage in disk blocks as large as 8K bytes.
.LI \f4rfs\f1
a distributed file system type\(emone of two supported in
Release 4.0; \f4rfs\f1 supports Remote File Sharing capabilities 
(including the ability to share files across a network of 
UNIX System V systems).
.LI \f4nfs\f1
a distributed file system type
originally introduced in the SunOS operating system 
(a BSD system derivative);  
\f4nfs\f1 supports Network File System capabilities (including the
ability to share files across a network in 
a heterogeneous environment). 
.LI \f4proc\f1
a file system type useful for 
debuggers and similar
utilities; it provides a mechanism for accessing the address space of
running processes.
.LI \f4fifofs\f1
a file system type that provides common access 
to pipe files.
.LI \f4specfs\f1
a file system type that provides a common code 
interface to all device files.
.LI \f4bfs\f1
a file system type that provides support for file
system independent booting; a \f4bfs\f1 file system
contains all the programs necessary for
the boot process.
.LE
.P
For more information about file system types in general, see
the \f2System Administrator's Guide\f1.
For more information about RFS and NFS, see the 
\f2Network User's and Administrator's Guide\f1.
.H 4 "Symbolic Links"
Release 4.0 introduces support for symbolic links.
A symbolic link is a file that contains the pathname of another file.  
References to the symbolic link are converted by the UNIX system kernel 
into references to the target file.
.P
Symbolic links make it possible to link directories.  This means 
that the logical
structure of a system's file tree can be rearranged without changing the 
physical location of files.
Symbolic links also allow links to a physical file to reside in a different 
physical file system.  This means that names can be linked across file 
systems that reside on different computers on a network\(emallowing 
a computer to create a logical directory 
tree that includes directories and files that physically reside on 
many different computers. 
.P
For more information about symbolic links, see the 
\f2Programmer's Guide: System Services and Application 
Packaging Tools\f1.
.H 4 "The Directory Tree"
In Release 4.0, the UNIX System V directory tree has been arranged to
facilitate sharing files, directories, and file systems in a networked
environment.
Release 4.0 divides the system into four standard file systems:
\f4/\f1 (called \f4root\f1), \f4/usr\f1, \f4/home\f1, and \f4/var\f1.
Within the standard file systems,
files
are organized by type, with each type occupying a separate branch
of the tree.  The directory tree defines three file types: machine 
private files,
architecture dependent files, and architecture independent files.
Because the directory tree
separates private files from shareable files, a system 
administrator
can easily mount a complete file system for distribution over a network.
.P
For more information, see the 
\f2System Administrator's Guide\f1.
.H 3 Networking
Earlier releases of UNIX System V provided tools for
developing network protocols and 
applications, specifically STREAMS and the Transport Level
Interface (TLI).   STREAMS defines standard interfaces
that allow networking architectures and higher-level
protocols to be independent of underlying protocols, drivers,
and media.  TLI defines an interface between applications
and transport level network protocols, relieving user
programs of the need to know the characteristics of
the transport protocol.
.SP
Early networking capabilities in the UNIX system 
were available through two optional
utilities packages: Basic Networking Utilities, which
provided basic file transfer capabilities between
UNIX System V systems via the
\f4uucp\f1 family of commands, and 
Remote File Sharing, a service that makes it
possible for a system to share files and devices with
remote UNIX System V systems.
.AB N
These tools and services continue to be important features of
UNIX System V in Release 4.0.  For information about STREAMS, see the
\f2Programmer's Guide: STREAMS\fP.  For information about TLI,
see \f2Programmer's Guide: Networking Interfaces\fP.  For information
about \f4uucp\fP services, see the \f2User's Guide\fP
and the \f2System Administrator's Guide\fP.  
For information about RFS, see the \f2Network User's and
Administrator's Guide\fP.
.AC
.P
New in Release 4.0 is support for TCP/IP and RPC, networking protocols 
that have become standards in the BSD networking environment,
and Network File System, a SunOS
file distribution facility.
Convergence with BSD networking is also seen in UNIX System V 
through its support
of \f4inetd\f1, a BSD network daemon, and the sockets interface.
In addition, Release 4.0 introduces new UNIX system 
networking technology
in the form of Network Selection and Name-to-Address Mapping.
.H 4 "TCP/IP (the DARPA Internet Protocol Suite)
In Release 4.0, UNIX System V supports TCP/IP, a family of network
protocols sometimes called the DARPA Internet Protocol Suite.
TCP/IP is a comprehensive set of protocols and commands
that support networking among systems of different types. 
.P
For more information about TCP/IP, see the \f2Network User's and
Administrator's Guide\f1.
.H 4 "Remote Procedure Call/External Data Representation
Release 4.0 includes Remote Procedure Call (RPC), a
protocol that makes it possible for a process to
call a procedure on a remote machine of a different
architecture, using the syntax and 
semantics of a local procedure call.
RPC allows a server program to use procedures on
remote machines like building blocks in complex applications.
.P
RPC uses External Data Representation (XDR) to encode data passed
between machines.  XDR is used to represent data in a standard way, so 
that a local process can call a procedure
residing on a machine of different architecture that is running 
the same or a different operating system.
.P
See the \f2Programmer's Guide: Networking Interfaces\f1 
for more information about RPC and XDR.
.H 4 "inetd"
In Release 4.0, UNIX System V supports \f4inetd\f1, a port monitor
(also called a daemon) that
waits for service requests from computers on a TCP/IP network.
\f4inetd\f1 is similar to \f4listen\f1, a UNIX System V 
port monitor that listens
for service requests from clients on any network that conforms
to the Transport Provider Interface.
When a connection request arrives over the network, \f4inetd\f1 
(like \f4listen\f1)
spawns the server process and passes the network connection to it.
.P
For more information about \f4inetd\f1, 
see the \f2Network User's and Administrator's Guide\f1.
.H 4 "Sockets"
Sockets is a networking interface widely used in BSD systems.
It is functionally similar to the UNIX System V Transport Level
Interface (TLI) in that it defines how a process accesses
the services of a transport protocol.
.P
Sockets is provided in Release 4.0 in a library
so that BSD applications that use sockets can migrate easily to
UNIX System V.
.P
For more information, see the \f2Programmer's Guide: Networking
Interfaces\f1.
.H 4 "Network File System"
Network File System (NFS) is
a facility for sharing files in a heterogeneous environment of machines, 
operating systems, and networks.  Sharing is accomplished by mounting 
a remote file system, then reading or writing files in place.  
Users are able to get directly to the files they want without 
knowing the network address of the data.  To the user, all NFS-mounted 
file systems look like private disks.  There are no apparent 
differences between reading or writing a file on a local disk, and 
reading or writing a file on a disk in another location.
.P
See the \f2Network User's and Administrator's Guide\f1
for more information.
.H 4 "Network Selection"
Release 4.0 introduces a feature to UNIX System V called
Network Selection.  Network Selection allows network
applications to choose the network over which they will communicate.
An application can select a network from a directory of networks 
that are available to the system.  If an application
fails to connect with its first choice, it can select different
networks until it finds one that meets its
service requirements and allows the connection.
.P
Network Selection frees an application from needing a network
selection embedded in its code.  This allows the application to run 
without modification on different systems that support different 
networks.
.P
For more information about Network Selection, see the \f2System
Administrator's Guide\f1 and the \f2Programmer's Guide: Networking
Interfaces\f1.
.H 4 "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.  The mechanism makes it possible for clients
to reach a server, even if the address on which the server 
is listening should change.
Name-to-Address Mapping also allows a client 
to reach a server over different networks.
.P
See the \f2Programmer's Guide: Networking Interfaces\f1 
for more information.
.H 3 "System Administration and Maintenance"
One of the goals of Release 4.0 is to simplify 
system administration and maintenance, while at the
same time adding functionality to meet the demands of increasingly
complex computer and network configurations.
Toward that goal, Release 4.0 provides new capabilities
in backup and restore operations, and software installation.
It also introduces an
enhanced administration interface that makes it easier for
a novice administrator to set up and maintain a system.
.P
The system administration features new in Release 4.0 are
described in the following sections.
For detailed information about these
features and for information about system administration in general,
see the
\f2System Administrator's Guide\f1.
.H 4 "Improved Backup and Restore Operations"
Release 4.0 provides
hardware independent backup and restore procedures (supporting
multiple bus architectures and multiple destination types,
such as tapes, floppy diskettes, and hard disks).
Multiple commands used as part of the backup procedure have been 
integrated in Release 4.0 into a single backup service.
.P
Key features of the backup and restore service include
.BL
.LI
a backup history log
.LI
on-line backups
.LI
automated backup initiation
.LI
mechanized restore requests.
.LE
.H 4 "Software Installation and Configuration Management Tools"
A software installation facility
in Release 4.0
provides a system administrator 
with installation procedures 
that are consistent across
software packages, releases, and machines.
It also provides tools 
and guidelines for developing add-on packages 
that take advantage of the standard software installation
script and menu interface.
Configuration tools allow an administrator easy access to information on
system configuration.
.H 4 "System Administration Menus (\f4sysadm\f1)"
Release 4.0 offers a new 
version of the menu interface for administration of a UNIX system.
The System Administration Menus (accessed using the \f4sysadm\f1
command) allow a user to
administer a UNIX system without knowledge of UNIX system commands.
Context-sensitive help messages make it possible for an administrator
to explore the interface with a minimum of documentation.
.H 3 "Real-Time Processing"
Historically, the UNIX system has been a general purpose 
time-sharing system.
Today, however, the system is seen more and 
more in environments
that require real-time processing.
.P
To support real-time processing, Release 4.0 introduces 
a new process-scheduler architecture and high-resolution
timing services.
(For more information than that provided in the following
descriptions, see the \f2System Administrator's Guide\f1 and the
\f2Programmer's Guide: System Services and Application Packaging
Tools\f1).
.H 4 "User-Controlled Process Scheduler"
A process scheduler
is kernel code that determines what program will run, when, and 
for how long.  The Release 4.0 architecture supports both
the traditional scheduling policy and the new real-time
scheduling policy.
Each process has its own scheduler properties,
which can be changed by users while the process is running.
The scheduler runs each process for a configurable ``time slice,''
then gives other processes a chance to run.
.P
The time-sharing scheduler policy manages processes in a traditional manner:
it dynamically adjusts time-sharing process priorities
in an attempt to give good response to all interactive processes.
.P
The real-time scheduler policy, on the other hand,
never changes a real-time process priority except as the result of
an explicit user request to change it.
Moreover, all real-time processes run before any other processes.
An application can perform its
time-critical tasks in real-time processes
and be assured that these processes will always
get priority over all non-real-time processes.
.P
Also to support real-time processing,
Release 4.0 provides new 
pre-emption points in the kernel\(empoints at which
the scheduler may switch control of the CPU from one process to another.
The additional pre-emption points improve 
system response time for high-priority processes.
.P
Using real-time processes, an application can guarantee fast, deterministic
response to its critical processes, on the order of 
microseconds rather than seconds.
.H 4 "High-Resolution Timers"
For applications that deal with very short time intervals,
Release 4.0 offers BSD system timing services, which give 
microsecond resolution.  These services include alarms,
interval timers, and a time-of-day clock.
(Some of these services were available on earlier releases,
but with lower timing resolution.)
.H 3 "Character-Based User Interface"
An earlier release of UNIX System V introduced the
Form and Menu Language Interpreter (FMLI)\(ema high-level
language interpreter that allows developers to write
user-friendly interfaces to their applications.
Release 4.0 provides
extensions to the Form
and Menu Language, including a way to interrupt executables,
a conditional statement (if-then-else), new built-in functions
\f4test\f1 and \f4expr\f1, and other improvements that give FMLI
programmers more control over the appearance and behavior of
their application interface.
.P
Framed Access Command Environment 
(FACE), also introduced in an earlier release, is an interface that 
allows a user
to see the UNIX system through frames containing menus
and forms.  In Release 4.0, FACE has been enhanced to be more
consistent with the version of FACE developed for UNIX System V/386 
Release 3.2, and adding applications to FACE has been made easier.
.P
For more information about FMLI, see the \f2Programmer's
Guide: Character User Interface (FMLI and ETI)\f1.  For
information about FACE, see the \f2User's Guide\f1.
.H 3 "Graphical User Interface and Windowing System"
As part of the effort to encourage a standardization of the
UNIX system, 
Release 4.0 offers
programming tools to support the OPEN LOOK\(tm Graphical
User Interface and the XWIN\(tm and X11/NeWS\(rg graphical
windowing systems.
.H 4 "XWIN Graphical Windowing System"
The XWIN Graphical Windowing System is a portable, 
network-transparent windowing system.
XWIN software creates a multi-layered server system on top of
the UNIX system; it gives the user the ability to
create multiple windows on a single display, with
each window running different applications.
.P
A windowing system keeps track of events and interfaces 
with client applications through a protocol system 
similar to the type of protocol system used by many
network operations.
XWIN software uses the X protocol for exchanging information 
between client applications and the server.
The X protocol gives application programs running on 
different systems, and appearing in
different windows, the ability to communicate with and use or display 
results from other application windows.
.VS 1
.P
For more information, see the 
.BT "Programmer's Guide: XWIN\(tm Graphical Windowing System" 
and the
.BT "Programmer's Guide: Porting the XWIN\(tm Server" .
.VE
.H 4 "X11/NeWS\(rg Graphical Windowing System"
The X11/NeWS Graphical Windowing System runs applications 
written to the X11 and NeWS
protocols.  Although the protocols are different, X11/NeWS provides 
an integrated environment in which both are supported, with 
both working off a single window manager.
This makes the GUI an extremely versatile 
graphical interface, offering more choices for both 
application developers and end users.
.VS 1
.P
For more information, see the
.BT "Programmer's Guide: X11/NeWS\(rg Graphical Windowing System" 
and the
.BT "Programmer's Guide: Porting the X11/NeWS\(rg Server" .
.VE
.H 4 "OPEN LOOK\(tm Graphical User Interface"
The OPEN LOOK Graphical User Interface defines a 
standard for the appearance
and function
of the graphical user interface and provides developers 
with application programmer interface 
toolkits (APIs).  APIs allow developers to manipulate
windows and window-supported graphics to achieve
the standard ``look and feel'' of OPEN LOOK Graphical
User Interface applications.
Two toolkits are provided as part of the OPEN LOOK 
software\(emone for writing
applications that operate on the XWIN server, and one
for writing X11/NeWS applications.
.VS 1
.P
For more information, see the
.BT "Programmer's Guide: OPEN LOOK\(tm Graphical User Interface" .
.VE
.H 3 "Internationalization"
With Release 4.0, AT&T continues to provide support 
for international environments in
the UNIX system.  New features in Release 4.0 that reflect
the internationalization effort include
.BL
.LI
support for multiple international code sets and multi-byte 
characters, and
support for character (as opposed to byte) processing
.LI
a message handling facility, which provides a means
of translating system messages to the user's native language
.LI
support for national conventions (forms and rules used
to communicate information).
.LE
.P
For information about features that support international
environments, see the
.BT "Migration Guide" .
.H 3 "C Language"
Release 4.0 incorporates enhancements to packages known by
the following names in earlier releases:
C Programming Language Utilities (CPLU), Advanced Programming 
Utilities (APU), and C Programmer Productivity Tools (CPPT) packages.  
The major features are:
.BL
.LI
Compilation modes corresponding to degrees of compliance with
ANSI C.
.LI
Dynamic linking, which allows different processes to share library
code at run time.
.LI
Dynamic tables, which provide the necessary support for compilation 
of applications with very large tables (e.g. macros, symbols, etc.).
.LI
Additional international support, allowing the international date 
and time to be set as a default, and support for customized internal 
character sets.
.LI
A new transparent object file format, ELF (Executable 
and Linking Format), 
which supports extensions to the C language, such as new types. 
ELF is flexible enough to support other programming languages, 
particularly C++.
.LI
Support tools for ELF and conversion tools for 
converting COFF (Common 
Object File Format) to ELF.
All tools handle both COFF and ELF objects and archives.
.LE
.P
See the \f2Programmer's Guide: ANSI
C and Programming Support Tools\f1,
the
.BT "ANSI C Transition Guide" ,
and the 
\f2Programmer's Reference
Manual\f1 for more information.
.H 3 "Extended Terminal Interface"
The Extended Terminal Interface (ETI) 
is a standard programming interface 
provided in Release 4.0
for character mode screen management and text operations.  ETI consists 
of three libraries, including
the \f4curses\f1 library and the \f4terminfo\f1 data base,
and the High Level Function library, which provides C subroutines 
for creating forms, menus, form editing functions, and panels.
.P
See the \f2Programmer's Guide: Character User Interface
(FMLI and ETI)\f1 for more information.
.H 1 "Product Description"
The UNIX System V source code product
consists of tapes (either nine-track or cartridge) that contain
Release 4.0 source code. 
Provided with the source code product is binary code
for the porting base processor, the AT&T 3B2/400 computer.
Binary code is available entirely on floppy diskettes,
or as a package consisting of five diskettes and two CTC
cartridge tapes.  
.P
The source product documentation reflects Release 4.0
on the porting base processor so that it can be used with the binary
code.  However, hardware-specific information has been
introduced only when necessary,
so that source code customers can easily revise the
documentation to produce their own hardware-specific manuals.
.P
The remainder of this section describes the UNIX System V 
Release 4.0 software and the document set.
.H 2 "Utilities Packages"
The utilities packages that make up Release 4.0 are
listed below.  Following the list are descriptions of the 
software that make up each package.
.BL
.LI
BSD Compatibility Package
.LI
Basic Networking Utilities
.LI
C Programming Language Utilities
.LI
Directory and File Management Utilities
.LI
Distributed File Systems Utilities
.LI
Editing Utilities
.LI
Encryption Utilities (CRYPT)
.LI
Essential Boot Utilities
.LI
Essential Utilities
.LI
Ethernet Media Driver Utilities
.LI
Extended Software Generation System Utilities
.LI
Framed Access Command Environment (FACE) Utilities
.LI
Inter-Process Communication (IPC) Utilities
.LI
Internet Utilities
.LI
Line Printer Spooling Utilities
.LI
Network File System Utilities
.LI
Networking Support Utilities
.LI
Graphical User Interface and Windowing System Utilities
.LI
Remote File System Utilities
.LI
Remote Procedure Call Utilities
.LI
Spell Utilities
.LI
System Administration Utilities
.LI
System Header Files
.LI
System Performance Analysis Utilities (SPAU)
.LI
Terminal Information Utilities
.LI
UFS Utilities
.LI
User Environment Utilities
.LI
Windowing Utilities
.LI
XENIX Compatibility Package
.LE
.H 3 "BSD Compatibility Package"
The BSD Compatibility package contains BSD commands and 
library routines that were not
merged with the UNIX System V base product.  It also includes software 
support for \f4sendmail\f1 and the BSD versions of 
\f4nroff\f1, \f4troff\f1, and \f4lp\f1.
.P
For more information about the BSD Compatibility package,
see the 
\f2BSD/XENIX\(rg Compatibility Guide\f1.
.H 3 "Basic Networking Utilities" 
The Basic Networking Utilities package enables
a UNIX system to communicate with other systems.
With the utilities and commands provided by the package, 
users can:
.BL
.LI
transfer files and send electronic mail
to other UNIX systems
.LI
communicate interactively with others using
UNIX systems or non-UNIX
systems
.LI
execute a restricted set of commands
on a remote system without directly logging in
on the remote system
.LI
call and log in to a remote system
.LI
call a remote terminal and allow the user of
the terminal to log in on a UNIX system.
.LE
.P
For information about using this package,
see the UNIX System V Release 4.0 \f2User's Guide\f1.
For information about administering this package,
see the 
.I "System Administrator's Guide"
and the Basic Networking Utilities manual pages in the
\f2System Administrator's Reference Manual\f1.
.H 3 "C Programming Language Utilities"
The C Programming Language Utilities package provides software
formerly in several utilities packages: 
.BL
C Programming Utilities
.LI
Advanced C Utilities
.LI
Software Generation Utilities
.LI
ETI/\f4curses\f1
.LI
C Programmer Productivity Tools
.LE
.P
See the \f2Programmer's Guide: ANSI C and Programming 
Support Tools\f1, 
the
.BT "Programmer's Guide: Character User Interface (FMLI and ETI)" ,
the
.BT "ANSI C Transition Guide" ,
and the
\f2Programmer's Reference
Manual\f1 for more information.
.H 3 "Directory and File Management Utilities"
The Directory and File Management Utilities package
consists of more than twenty-five commands that provide
enhanced file and directory manipulation capabilities.
With these commands, a user can do the following things:
.BL
.LI
search directories or files
.LI
compare the contents of directories or files
.LI
manipulate the contents of files.
.LE
.P
For more information, see the
.I "User's Guide"
and the Directory and File Management Utilities manual pages
in the
\f2User's Reference Manual\f1.
.H 3 "Distributed File System Administration Utilities"
The Distributed File System Administration Utilities (DFS) 
package provides 
a common administrative interface to Remote File Sharing 
and Network File System.  Commands installed by the DFS 
Administration Utilities
package allow an administrator 
to share and mount both RFS and NFS resources.
DFS utilities must be installed to run RFS and NFS.
.P
See the 
\f2Network User's 
and Administrator's Guide\f1
for more information.
.H 3 "Editing Utilities"
The Editing Utilities package provides
three related editors:
two line editors (\f4edit\f1 and \f4ex\f1) and a screen 
editor (\f4vi\f1).
The \f4edit\f1 editor is mainly for novice users.
The \f4ex\f1 editor is an advanced version of
\f4edit\f1 and is for experienced users.
The \f4vi\f1 editor is intended for all users;
it allows the user to 
view a screen of text at
one time and move the terminal's cursor directly to
any position in the file.
.P
For more information, see the editing tutorials in the 
\f2User's Guide\f1
and the Editing Utilities manual pages in the \f2User's 
Reference Manual\f1.
.H 3 "Encryption Utilities (CRYPT)"
The Encryption Utilities package provides an
encryption mechanism for protecting
information stored in the computer.
Using the facilities of this package gives additional protection
beyond that obtained through login IDs, passwords, and permission modes.
When this package has been installed, the
encryption mechanism is available by using the \f4crypt\f1 command,
as well as in the editors \f4ed\f1, \f4edit\f1, \f4ex\f1, and \f4vi\f1.
.P
The Encryption Utilities package has restricted 
distribution
and is provided only with computers sold within the United States.
.P
For more information, see the
\f4crypt\f1(1),
.UI ed (1),
.UI edit (1),
.UI ex (1),
and
.UI vi (1)
manual pages in the
\f2User's Reference Manual\f1.
.H 3 "Essential Boot Utilities"
The Essential Boot Utilities package provides the utilities required
for file-system-independent installation of Release 4.0.
.H 3 "Essential Utilities"
The Essential Utilities package
consists of the operating system kernel,
a minimum set of device drivers,
and the most essential and commonly-used
commands, including commands to invoke the
System Administration Menus (\f4sysadm\f1) and
the Form and Menu Language Interpreter (a
programmer interface for character mode screen
management).
The Essential Utilities also include
installation and configuration management utilities,
and message management and monitoring utilities.
.P
For additional information about the software
in the Essential Utilities package
and how to use it, see the \f2User's Guide\f1,
the \f2System Administrator's Guide\f1,
the Essential Utilities manual pages in the
.I "User's Reference Manual"
and \f2System Administrator's Reference Manual\f1,
and the \f2Programmer's Guide: Character User Interface
(FMLI and ETI)\f1.
.H 3 "Ethernet Media Driver Utilities"
The Ethernet Media Driver Utilities package provides the software
to drive an Ethernet board on an AT&T 3B2 computer.
.H 3 "Extended Software Generation System Utilities"
This package provides additional software generation
utilities.
.H 3 "FACE Utilities"
Framed Access Command Environment (FACE) is a package that provides
a character-based
menu interface to the UNIX system intended for non-expert 
computer users.  It provides a hierarchy of forms and menus through which
a user can execute basic UNIX system commands for file editing and 
text manipulation.  It also includes tools for creating a menu of services 
through which a user can access application packages.
.P
See the \f2User's Guide\f1 for a tutorial that explains how to use
FACE.
.H 3 "Inter-Process Communication (IPC) Utilities"
The Inter-Process Communication (IPC) Utilities
package permits cooperating processes to share data and
to communicate with each other.
It contains system calls for obtaining, controlling, and performing
operations on the three types of IPC facilities:  messages, semaphores,
and shared memory.
In addition, there are commands to check the status
of and to remove IPC facilities.
.P
For more information, see the
\f2Programmer's Guide: System Services and Application 
Packaging Tools\f1
and the Inter-Process Communication Utilities
manual pages in the
.I "User's Reference Manual"
and the
\f2Programmer's Reference Manual\f1.
.H 3 "Internet Utilities"
The Internet Utilities package installs the TCP/IP network protocols,
also known as the DARPA Internet Protocol Suite, as well as commands
that allow users to login to remote systems, execute
commands on remote systems, and copy files from 
remote systems.
.P
For information about TCP/IP, see the 
\f2Network User's and
Administrator's Guide\f1.
.H 3 "Line Printer (LP) Spooling Utilities"
The Line Printer (LP) Spooling Utilities package
provides the temporary storing (spooling) of data until it 
can be printed.
.P
With LP spooling, print requests can
be entered at a terminal and printing can
take place without tying up the terminal.
Spooling also enables many users to share
a printer, or several printers, efficiently.
The commands in this package
can perform the following functions:
.BL
.LI
customize the system so that it will spool
to a group of line printers
.LI
group printers into logical classes to
maximize the throughput of the printers
.LI
queue print requests, thus allowing a
print request (job) to get printed on the next
available printer in the appropriate class
.LI
cancel print requests, so a job that is
no longer needed will not be printed
.LI
start and stop the LP spooling software from processing
requests
.LI
change the configuration of printers
.LI
find the status of the LP
scheduler
.LI
restart any printing that was not completed
when the system was powered down
.LI
connect multiple computers
into a network so that the users of one computer can use 
any of the printers connected to the other computers in the network.
.LE
.P
For information about using this package,
see the
.I "User's Guide"
and the \f2User's Reference Manual\f1.
For information about administering this package,
see the
.I "System Administrator's Guide"
and the 
\f2System Administrator's Reference Manual\f1.
.H 3 "Network File System Utilities"
The Network File System Utilities package provides
the facilities needed to share resources among
computers in a heterogeneous environment.
It requires the Networking Support Utilities package,
UDP/IP (transport protocols provided by the
Internet Utilities package), and the Distributed File System
Administration Utilities package.
.P
For more information about Network File System, see
the \f2Network User's and Administrator's Guide\f1.
.H 3 "Networking Support Utilities"
The Networking Support Utilities package 
installs the STREAMS mechanism as well as software support 
for Network Selection, the Service Access Facility,
and Transport Level Interface (TLI).
.P
Service Access Facility utilities include the 
network daemon \f4listen\f1, as well as commands for 
administering it.
.P
The Networking Support Utilities package must be installed to
take advantage of services provided by 
the Remote File Sharing Utilities package and Network File System 
Utilities package.
.H 3 "Graphical User Interface and Windowing System Utilities"
The Graphical User Interface and Windowing System
Utilities package installs all the software that 
makes up the
Graphical User Interface product, including
.BL
.LI 
AT&T Xlib, OPEN LOOK toolkits and client software
.LI
the XWIN Graphical Windowing System
.LI
the X11/NeWS Graphical Windowing System
.LI
tNt, an X11/NeWS toolkit
.LI
AT&T XView, a toolkit for porting SunView applications
.LI
NeWS client software, including window manager and file
manager software.
.LE
.H 3 "Remote File Sharing Utilities"
The Remote File Sharing Utilities package provides the 
facilities needed to share resources transparently among 
computers running UNIX System V.  It requires the 
Networking Support Utilities package, the Distributed
File System Administration Utilities, and a transport provider 
that conforms to the AT&T
Transport Provider Interface, such as the STARLAN NETWORK 
or TCP/IP
(provided in the Internet Utilities package).
.P
For more information about Remote File Sharing, see
the \f2Network User's and Administrator's Guide\f1.
.H 3 "Remote Procedure Call Utilities"
The Remote Procedure Call package provides a remote 
operation capability.
The package includes RPC, XDR, and sockets libraries.
.P
For more information about RPC, see the 
\f2Programmer's Guide: Networking Interfaces\f1.
.H 3 "Spell Utilities"
The Spell Utilities package contains a program
and dictionary files that enable a user to check for
misspelled words in a file. 
The performance of \f4spell\f1 can be monitored by reviewing
a file that contains a history of misspelled words.
.P
For more information, see the
Spell Utilities manual pages in the \f2User's Reference Manual\f1.
.H 3 "System Administration Utilities"
The System Administration Utilities package
contains system administration utilities and commands intended to
be used by someone with
responsibility for managing the hardware, software,
and users on a UNIX system.
It includes
backup and restore facilities, the \f4edsysadm\f1 and 
\f4delsysadm\f1 commands
(for customizing the menu interface), 
configuration 
management tools (in addition to those provided in
the Essential Utilities), and all tools for packaging.
.P
The commands provided in the package perform functions similar
to those available through the System
Administration Menus described in the \f2System Administrator's
Guide\f1; however, these commands offer more flexibility and their use
requires a greater understanding of how the UNIX system works.
.P
For more information, see the
.I "System Administrator's Guide"
and the System Administration Utilities manual pages in the
\f2System Administrator's Reference Manual\f1.
.H 3 "System Header Files"
The System Header Files contain information about
UNIX System V Release 4.0 that is 
used only in a program development environment.
The System Header Files package should be installed with
the C Programming Language Utilities package or another
language product.
.H 3 "System Performance Analysis Utilities (SPAU)"
The System Performance Analysis Utilities package provides
performance tools that measure and display the
following kinds of information:
processor utilization, buffer and file access activity,
terminal device activity, disk input/output activity,
system calls, process switching, swapping activity, queue activity,
and inter-process communication (IPC) activity.
.P
To make the best use of these tools, 
follow the strategies outlined in the \f2System Administrator's
Guide\f1.
See also the related manual pages in the
.I "User's Reference Manual"
and the \f2System Administrator's Reference Manual\f1.
.H 3 "Terminal Information Utilities"
The Terminal Information Utilities package contains
a database (\f4terminfo\f1)
that allows programmers to write
programs to manipulate screens
(and parts of screens, such as function keys and soft labels)
of video display terminals.
.P
As delivered, the \f4terminfo\f1 database contains descriptions
of over 150 terminals.
.P
For more information, see the
\f2Programmer's Guide: Character User Interface (FMLI and ETI)\f1.
.H 3 "UFS Utilities"
The UFS Utilities package includes software support for
\f4ufs\f1\(ema file system type based on the BSD system ``fast 
file system'' that 
stores data in
blocks as large as 8K bytes.
.P
For information about \f4ufs\f1, see the \f2System Administrator's
Guide\f1.
.H 3 "User Environment Utilities"
The User Environment Utilities package consists of
commands that can be used to do the following things:
.BL
.LI
perform mathematical calculations
.LI
check or change the executing environment of commands
.LI
schedule commands to be executed at a later time
.LI
interact with more than one session from
any terminal and switch easily between these virtual
layers, as if logged in from several
terminals simultaneously
(this feature works with any terminal,
whereas the Windowing Utilities
package works only with terminals that have
specific capabilities, such as the AT&T 630 MTG, a dot-matrix
display terminal).
.LE
.P
For more information, see the
.I "User's Guide"
and the User Environment Utilities manual pages
in the
\f2User's Reference Manual\f1.
.H 3 "Windowing Utilities"
The Windowing Utilities package provides
the software that is commonly required by 
AT&T windowing terminals
(such as the AT&T 630 MTG)
to create, delete, and manipulate terminal windows,
query terminal window status, and
display statistics about usage of windowing routines.
.P
For more information about this package,
see the \f4layers\f1(1) manual page in the \f2User's Reference 
Manual\f1 and
the \f4libwindows\f1(3X) manual page in the \f2Programmer's 
Reference Manual\f1.
.H 3 "XENIX Compatibility Package"
The XENIX Compatibility Package contains commands that are specific 
to applications developed for XENIX systems and XENIX system
commands that will not be 
supported beyond 
Release 4.0.  These include the XENIX system file and record locking 
interface (\f4locking\f1) and
system calls that support the XENIX system shared memory and semaphores 
(contained in a library called \f4libx\f1).
.P
For more information about the XENIX Compatibility Package, see the
\f2BSD/XENIX\(rg Compatibility Guide\f1.
.H 2 "The Release 4.0 Document Set"
Available with the UNIX System V Release 4.0 source code product is
a full set of documentation that addresses the needs of users,
system administrators, programmers, and porters.
The documentation supports Release 4.0 on the porting base
processor\(emthe AT&T 3B2/400 computer.
.P
The Release 4.0 document set includes both 
guides and reference manuals.
Guides contain conceptual and procedural information;
they tell when and why to do something, as well as how to do it.
A guide is usually the best introductory text (tutorials are often
included),
yet it is organized so that experienced users can easily skip
to the information
they need.
.P
Reference manuals contain complete descriptions (traditionally
known as ``manual pages'' or ``man pages'') of commands, utilities, 
system calls, library functions, or system file formats.
The assumption in a reference manual is that the user already knows when
and why a task should be done.
Although descriptions are complete, every attempt has been 
made to keep them
to one page;
as a result they are sometimes
cryptic.
A reference manual is an efficient source of information
once you've become familiar with the product.
.VS 1
.P
Customers who purchase a source code license for UNIX System V
Release 4.0 receive the Source Code Product Machine Readable Documentation (SCP MRD),
a full set of reference
documentation (manual pages and proprietary documents) and formatting tools 
distributed on a 9-track tape.
Provided both on the tape and in hard-copy form are
software notes and
source code build instructions.
Provided only in hard-copy form is a booklet called
.BT "Source Code Product Read Me First" ,
which explains where to find out how to generate hard-copy documentation
from the tape.
.P
Customers who purchase the optional Documentation 
Reproduction Provision (DRP)
receive a different tape that contains all the Release 4.0
guide material,
in addition to all the manual pages that are included with the SCP MRD.
With the DRP, customers also purchase
the right to reproduce the documentation, or to customize it
to reflect the specifics of their UNIX System V implementations
and make it available to their customers.
Provided only in hard-copy form to DRP customers is a booklet called
.BT "Documentation Reproduction Provision Read Me First" ,
which explains how to generate hard-copy documentation
from the tape.
.VE
.P
Below is a list of the volumes that make up the 
Release 4.0 document set.  Following 
the list are descriptions of the contents of each volume.
.VS 1
Documents in groups that are marked ``proprietary'' may not
be reproduced for distribution with sublicensed products.
.VE
.SP
.B "GENERAL USE AND SYSTEM ADMINISTRATION"
.BL
.LI
Product Overview and Master Index
.LI
User's Guide
.LI
User's Reference Manual
.LI
System Administrator's Guide
.LI
System Administrator's Reference Manual
.LI
Network User's and Administrator's Guide
.LE
.SP
.VS 2
.ne 10
.VE
.B "PROGRAMMING"
.P
.B "General Programmer's Series"
.BL
.LI
Programmer's Guide: ANSI C and Programming Support Tools
.LI
Programmer's Guide: System Services and Application Packaging Tools
.LI
Programmer's Guide: Character User Interface (FMLI and ETI)
.VS 1
.LI
Programmer's Guide: OPEN LOOK\(tm Graphical User Interface
.LI
Programmer's Guide: XWIN\(tm Graphical Windowing System
.LI
Programmer's Guide: X11/NeWS\(rg Graphical Windowing System
.VE
.LI
Programmer's Guide: POSIX Conformance
.LI
Programmer's Guide: Networking Interfaces
.LI
Programmer's Reference Manual
.LE
.NE 6
.P
.B "System Programmer's Series"
.BL
.LI
Programmer's Guide: STREAMS
.LI
Device Driver Interface/Driver-Kernel Interface (DDI/DKI) Reference Manual
.LE
.VS 1
.P
.B "System Porter's Series (Proprietary)"
.BL
.LI
Programmer's Guide: Porting the Kernel
.LI
Programmer's Guide: Porting the XWIN\(tm Server
.LI
Programmer's Guide: Porting the X11/NeWS\(rg Server
.LE
.VE
.SP
.B "RELEASE-SPECIFIC INFORMATION"
.P
.B "General"
.BL
.LI
Migration Guide
.LI
ANSI C Transition Guide
.LI
Software Notes
.LI
BSD/XENIX\(rg Compatibility Guide
.LE
.VS 1
.P
.B "Release-Specific Documents Only for Source Code Licensees (Proprietary)"
.BL
.LI
Source Code Product Build Instructions
.LI
Source Code Product
Read Me First
.LI
Source Code Product Machine Readable Documentation Release Notes
.LI
Documentation Reproduction Provision
Read Me First
.LI
Documentation Reproduction Provision Machine Readable 
Documentation Release Notes
.LI
Technology File Mapping Guide
.LE
.VE
.H 3 "Product Overview and Master Index"
In addition to a brief introduction to UNIX System V and a 
summary of Release 4.0 features,
the \f2Product Overview and Master Index\f1 contains both a
standard 
index and a permuted index that covers all the 
.VS 1
non-proprietary 
.VE
material in the 
source product documentation set.
The standard master index covers all the guide and tutorial 
information in the Release 4.0 document set
and 
indexes manual pages by name.
The master permuted index contains entries from all the manual pages in the document set.
(A permuted index indexes manual pages by
key phrase).
.H 3 "User's Guide"
The \f2User's Guide\f1 describes what you need to know to get 
started using the UNIX system, including how to use the basic commands 
to create and manipulate files.  In addition, it includes 
tutorials describing FACE, \f4ed\f1, \f4vi\f1, the shell, \f4awk\f1, 
and how to send 
mail and files to other users.  It also includes \f4vi\f1
quick reference information.
.H 3 "User's Reference Manual"
The \f2User's Reference Manual\f1 describes each of 
the UNIX System V user commands.  
Each description includes a synopsis of the command syntax and 
an explanation of how it is used; also supplied where appropriate 
are diagnostic indications, warnings, examples of use, and where to
find related information.
.H 3 "System Administrator's Guide"
The \f2System Administrator's Guide\f1 explains how to perform 
administrative tasks,
including managing file systems and users, setting up basic networking, 
maintaining security, tuning the system to optimize performance, 
and administering printers.  Tasks are 
organized by the menu layout of \f4sysadm\f1, the administration interface.
.H 3 "System Administrator's Reference Manual"
The \f2System Administrator's Reference Manual\f1
describes each of the UNIX System V administration commands.  
Each description includes a synopsis of the command syntax,
an explanation of usage, and, where appropriate,
diagnostic indications and warnings.
.H 3 "Network User's and Administrator's Guide"
The \f2Network User's and Administrator's Guide\f1
tells how to use and administer the network facilities 
provided with UNIX System V.  It includes descriptions of
administering and using Remote File Sharing (RFS), Network File
Sharing (NFS), and TCP/IP.
.H 3 "Programmer's Guide: ANSI C and Programming Support Tools"
This guide discusses the UNIX system 
programming environment and utilities (e.g., compilers, 
debuggers) and provides details of the C language, file formats, 
the link editor, libraries, and tools.
.H 3 "Programmer's Guide: System Services and Application Packaging Tools"
This guide 
tells how to develop an application
package under UNIX System V.  It describes how to use the UNIX
system services provided by the kernel, such as file and record 
locking, interprocess communication, the process scheduler, and 
symbolic links.  It also describes how to use libraries of
routines in software development in general, and standard tools 
to package application software for easy installation on a running 
system.
.H 3 "Programmer's Guide: Character User Interface (FMLI and ETI)"
This guide 
describes tools a programmer can use to interface with a user at 
a terminal that does not have graphics capabilities.
These tools range from an interpretive language that makes it easy 
to develop forms and menus (FMLI) to libraries of routines 
(ETI/\f4curses\f1) that enable the programmer to work with high-level 
constructs, such as windows, or do low-level
character placements.  Routines remain independent of terminals 
by using a database that describes the capabilities of a terminal and 
the way it performs various operations.
.VS 1
.H 3 "Programmer's Guide: OPEN LOOK\(tm Graphical User Interface"
This manual contains two guides\(emone for programmers 
using OPEN LOOK software widgets, and another for OPEN LOOK 
software end users 
with limited experience with the UNIX system and 
windowing environments.
The programmer's guide provides overview information and 
a description of each 
OPEN LOOK software widget, as well as a series of programs
that acts as a guide to learning how to program with 
widgets.
.P
In addition to end user information, the user's guide
contains information valuable to installers and 
system administrators.
.H 3 "Programmer's Guide: XWIN\(tm Graphical Windowing System"
This guide is divided into five sections, each covering
a different interface level of the XWIN software product.  
First described is Xlib, the C language interface.  The
document explains display functions, connecting to the X server, 
window functions, graphics functions, window manager functions, 
events handling, and application utility functions.  The second section
of the manual deals with the mid-level toolkit called the X Toolkit 
Intrinsics.  The X toolkit is the interface 
for developers creating user applications that are compatible
with the X server.
Section three of the manual deals with the Athena widget set and 
the make-up of the X toolkit, and section four
describes the X protocol.  A final section includes
technical papers and supporting documentation that clarify 
various facets of the XWIN product.
.H 3 "Programmer's Guide: X11/NeWS\(rg Graphical Windowing System"
This book is made up of four smaller guides: ``The X11/NeWS Server
Guide,'' the ``NeWS Programmer's Guide,'' and the ``tNt
Technical Reference Manual,''
and the ``XView Programming Manual.''
The server guide assumes the reader is reasonably
familiar with the Adobe Postscript\(rg language.  It describes
the initialization process and gives examples of how to modify 
an initialization routine by customizing Postscript 
language files.  
It also discusses different ways to run NeWS 
graphical windowing system programs.
.P
The programmer's guide also assumes the reader's familiarity 
with the Postscript language.  It describes all the basic concepts 
of NeWS graphical windowing system 
programming; provides a syntactic analysis for 
each NeWS software operation; and includes code examples that 
demonstrate the use of NeWS software operator and type extensions,
including PostScript extensions such as Canvases, NeWS Imaging,
NeWS Types, Classes, and the window manager.
.P
The tNt reference manual documents ways to
manipulate 
the appearance and function of the server window and 
design applications that observe the OPEN LOOK
graphical user interface standard.  It
describes the details of the programmer's interface to
the server components, and 
depicts, in the form of graphs
and alphabetical entries, the relationship of
functional groups within classes of objects.
It also lists each class, along with the methods and routines that 
define it.
.P
The XView programming manual
presents an overview of XView programming as an 
object-oriented programming system.
The manual includes a tutorial that demonstrates the structure of 
XView programs, and it
describes what is involved in initializing XView and 
creating XView objects
such as frames and subwindows.
Also documented are individual XView packages, such as
frames, canvases and openwin objects,
panels, text subwindows,
scrollbars, menus,
notices, cursors, and icons.
.VE
.H 3 "Programmer's Guide: POSIX Conformance"
In accordance with POSIX documentation requirements,
this guide
describes how UNIX System V conforms to POSIX and provides the 
implementation-specific details of that conformance.
.H 3 "Programmer's Guide: Networking Interfaces"
This guide
describes the Transport Level Interface (TLI), its capabilities and 
applications, and other network development tools, such
as RPC and the Network Selection facility.
.H 3 "Programmer's Reference Manual"
The \f2Programmer's Reference Manual\f1 contains manual pages for 
UNIX System V programming commands, 
libraries, system calls, file formats, and 
miscellaneous information used by programmers.
.H 3 "Programmer's Guide: STREAMS"
The \f2Programmer's Guide: STREAMS\f1
describes the user-level STREAMS facilities 
and explains how to use STREAMS facilities to write 
UNIX System V kernel modules and device drivers.  It includes 
a summary of kernel-level
data structures, STREAMS message types, and specifications
of kernel utility routines.
.H 3 "Device Driver Interface/Driver-Kernel Interface (DDI/DKI) Reference Manual"
The \f2Device Driver Interface/Driver-Kernel Interface (DDI/DKI)
Reference Manual\f1 provides reference information for creating, 
modifying, and maintaining drivers that run on UNIX System V Release 
4.0.  It defines the entry point routines that must be written, 
the kernel functions that should be used, and the data structure with 
which the drivers interact.
.VS 1
.H 3 "Programmer's Guide: Porting the Kernel (Proprietary)"
This guide describes 
how to port the UNIX System V kernel from Release 3 to Release 4.0.
It identifies the machine dependencies that reside in the kernel
and the C Compilation System.  It does \f2not\f1 
provide solutions
for handling machine-dependent sections of code.
.H 3 "Programmer's Guide: Porting the XWIN\(tm Server (Proprietary)"
This manual provides information about
porting the XWIN server to the AT&T 6386 WGS family
of computer workstations.
A description of modifications that have been made to
XWIN software so that it runs in both a
UNIX System V Release 3.2 and a Release 4.0 environment is included.
Additional information is
provided for porting the XWIN server to other devices
and operating systems not already
supported by code.  The manual explores sample machine
environments and delineates where changes have to be
made. 
.H 3 "Programmer's Guide: Porting the X11/NeWS\(rg Server (Proprietary)"
This manual is made up of four smaller documents: the
``X11/NeWS Porting Guide,'' the ``Shapes Porting Guide,'' 
the ``Shapes Reference 
Manual,'' and the ``Shapes Internals Architecture''
manual. 
The ``X11/NeWS Porting Guide''
covers the information necessary to port X11/NeWS software to
non-AT&T hardware.  It covers hardware and memory requirements,
device requirements, and network requirements.  
This document is written for developers familiar with porting
windowing systems to hardware platforms.  
.P
The ``Shapes Porting Guide''
contains topics to consider when porting Shapes to
devices that are not supported by Shapes code.  The document is
aimed at the programmer with a C programming background who is
familiar with the
UNIX operating system.  In addition, the reader should be 
well-acquainted with
Shapes, especially screen object and low-level rendering.
.P
The ``Shapes Reference Manual'' documents
external operators, attributes, and macros of the Shapes 
graphics library.
.P
The ``Shape Internals Architecture'' manual describes 
the internal architecture of the code and how it relates 
to porting considerations.  The document is written for 
applications programmers who are familiar with interactive 
computer graphics, C programming, the UNIX operating system, 
and the graphics library.
.VE
.H 3 "Migration Guide"
The \f2Migration Guide\f1 
presents an overview of Release 4.0 features and 
describes the major differences between Release 4.0 
and previous releases of UNIX System V.
.H 3 "ANSI C Transition Guide"
The \f2ANSI C Transition Guide\f1 
describes techniques for writing new and upgrading 
existing C code to comply with the ANSI C language specification.
.H 3 "Software Notes"
\f2Software Notes\f1 offers additional information about 
UNIX System V Release 4.0, including operating and
programming tips and
miscellaneous information that was not available in time to 
include in the Release 4.0 guides and manuals.
.H 3 "BSD/XENIX\(rg Compatibility Guide"
The \f2BSD/XENIX\(rg Compatibility Guide\f1 
documents the supplemental BSD system and XENIX 
system commands and features that
are provided by the BSD Compatibility Package and
the XENIX Compatibility Package.
The manual contains both user-level guide material and
manual pages.
.VS 1
.H 3 "Release-Specific Documents Only for Source Code Licensees (Proprietary)"
In addition to the reference manuals and guides, 
the Release 4.0 documentation set includes a 
number of other documents
intended for source code licensees only.
.P
The 
.I "Source Code Product Build Instructions" 
describes the software and documentation that are included in the Source 
Code Product.
It lists all the files included on the source product tapes;
explains how to extract Release 4.0 software and documentation from the
source tapes; tells you how to build and install
source code on 3B2 and non-3B2 
computer systems;
and describes how to get started printing Release 4.0 documentation.
It also 
identifies dependencies and includes notes on 
problems you might encounter 
while building and installing UNIX System V from the source code.
.P
The
.I "Source Code Product Read Me First" 
is a roadmap to the source code product for UNIX System V Release 4.0.
It briefly describes the major components of the product and tells you where
to find further information on each,
such as how to build and install the software and documentation components
provided on the source product tapes.
.P
The 
.I "Source Code Product Machine Readable Documentation Release Notes" 
describes the contents of the SCP MRD
tape, both documents and tools.
It 
identifies additional tools you must have available to format 
the documents provided on the tape, and
explains
how to use the tools to build your own documents.
It also includes notes on
incompatibilities and other problems you might encounter.
.P
The
.I "Documentation Reproduction Provision Read Me First" 
explains how to extract and print the documentation from the
Documentation Reproduction Provision MRD tape
for UNIX System V Release 4.0.
.P
The 
.I "Documentation Reproduction Provision Machine Readable Documentation Release Notes"
describes the contents of the DRP MRD
tape, both documents and tools.
It 
identifies additional tools you must have available to format 
the documents provided on the tape, and
explains
how to use the tools to build your own documents.
It also includes notes on
incompatibilities and other problems you might encounter
and a list all files supplied on the DRP MRD tape.
.P
The 
.I "Technology File Mapping Guide" 
specifies the files in Release 4.0 that are applicable to specific
technology, and therefore available to licensees of that 
technology as provided in the technology licensing section 
of the Release 4.0 schedule.
.VE
.H 1 "Related Products"
AT&T provides a comprehensive collection of software products 
that work with UNIX System V Release 4.0.
Products fall into a number of categories, including
networking, programming, database management, and general applications.
.P
For specific information about software products, see the 
.I "AT&T Computer Software Catalog" .
