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Module 1
ABOUT THIS BOOK

INTRODUCTION

This book describes the UNIX operating system user commands. It is based on AT&T UNIX System V Release 4 and Berkeley Software Distribution(BSD) 4.3. It provides you the knowledge and insight to fully use the power of the UNIX System.

You may ask what exactly is UNIX? UNIX is several things. It is a computer operating system. It is also a large set of utility programs. These utilities include general user, programmer, typesetting, communication, and administrative commands.

Because UNIX is a large computer operating system environment, only the more popular User Commands (over 160) will be discussed. An overview of the UNIX System, an MS-DOS to UNIX command cross reference, and a VMS to UNIX command cross reference are also included.

This book is designed for a broad range of users. It is for beginners who wish to learn UNIX from scratch. It provides intermediate and advanced users a complete reference containing command examples that are useful and provide insight on how to become a UNIX master. Finally, it serves the classroom instructor as an instructionally designed UNIX textbook.

The UNIX System is a sophisticated set of computer programs. The UNIX kernel is the main operating system program. The remainder of the System is made up of many powerful commands. The User Commands are available to all UNIX users.

The UNIX kernel (the operating system) is the software that controls and manages the computer system and the peripherals that are attached. The kernel controls the computer hardware, providing an interface between the application level software and the computer hardware. By managing the computer resources, the kernel can use a single computer and its peripherals to provide multiple users with the computer environment they need.

The UNIX User Commands provide the user with an extremely flexible and powerful computer environment. There are general service, file management, file processing, line printer (spooling), system status, intersystem communications, electronic messaging, pattern matching, text editing, command execution, and shell programming commands available. The most powerful and useful command is the UNIX shell. The Korn shell (ksh) is an enhanced version of the Bourne shell (sh). It is used in Illustrated UNIX as the default UNIX shell.

The ksh is a sophisticated command interpreter. It does not display user friendly menus. Instead, it displays a prompt and a cursor, requiring you to enter your command from the keyboard. A command is the instruction you type on your keyboard that informs ksh what program to execute. To a new user, ksh may appear to be intimidating because of its terse and cryptic commands and syntax. It is important and necessary that you learn and understand how ksh works. Most users think of ksh (or some other shell) as UNIX. This is actually a valid assumption since you interact with ksh and not the operating system.

ORGANIZATION

This book is organized into easy-to-read, example-packed modules, to fit the broad range of users it addresses. These modules contain Description, Applications and Typical Operation sections.

Because this book covers two versions of the UNIX operating system, it is necessary to distinguish between commands supported by one version and not the other. This problem also arises with different types of shells (command interpreters).

Both versions of the operating system support the Bourne shell (sh). The SV version supports an enhanced shell, the Korn shell (ksh). The BSD operating system supports the C shell (csh), a more interactive oriented shell. The ksh is the standard shell on SV. It can be purchased for most BSD systems.

If a command is only supported by one of the shells, then the module is marked accordingly. If the module is only usable if you have the csh, the module is marked as such. The same is true of modules only usable if the ksh is available.

If a command is only found on one system, i.e., System V or BSD, the entire module is specified as that type of module. System V modules are marked as SV and Berkeley modules are marked as BSD.

If a command is shared by both systems, then the base information in the module is System V with BSD text interventions. The inserts of BSD related material are clearly marked. For example,


BSD (Berkeley)
This text only appears where BSD information applies.
Options Under the Options section the options discussed in the BSD section are either in addition to the SV options, perform a different function, or are specifically marked as unsupported.


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