Preface

Intended Audience

The intent of this document is to help the reader with little to no Unix experience understand, and be able to comfortably use a Unix system. This e-text is intended for people who have some experience using computers, but not necessarily with command line interfaces or with the Unix operating system. While one does not have to be a programmer to understand and learn from this hypertext, it will help if the reader has some basic computer sophistication; i.e. understands the concept of files, file system navigation, application programs, input/output devices, etc. The author assumes the reader truly does want to learn and understand the commands and concepts which comprise the Unix operating system; because if not, this nor any other text will provide much help.

This text is not for everyone however; it is NOT intended for:

advanced or Unix power users (unless to refresh ones memory)
system administrative tasks
Unix/Linux installation instructions (including package management)
kernel tuning techniques
Unix networking concepts

While all of this material is quite worthy and interesting, it is simply beyond the scope of this text.

The author's sincerest intention is that the reader of this text will learn to appreciate Unix and embrace the Unix philosophy as much as he does.

Content and Organization

The Unix topics and commands presented in this hypertext are meant to cover the gamut of Unix systems and flavors. While there are many installations running the latest freely available version of Linux, there are also many environments where users are running an early 1990's version of Unix. Thus, not all of the latest and greatest new commands are documented here. However, the commands documented here should be supported on a very wide variety of Unix installations and terminal configurations. The goal of this text is to present concepts, topics and commands that are supported across the broadest possible variety of Unix (and/or Linux) implementations.

Following this philosophy of broad support in this text is the treatment of the user interface. A plethora of graphical user interfaces (GUIs) are available for Unix systems today. Most of these graphical user interfaces provide very powerful and sophisticated tools, and best of all, many are free. However, not every installation is going to have the latest and greatest GUI installed. Because of this, this text will focus upon a basic command line interface. At some point in time (believe me), all Unix users will have to use a command line interface to accomplish a necessary task.

This text is organized in a manner such that simple Unix commands and Operating System concepts are presented in the early sections, while more complicated and sophisticated concepts are presented in the later sections. It is the author's recommendation that readers of this text initially begin at the beginning and only proceed to later sections when the material in the current section is well understood.

In addition, each section that presents Unix shell commands will contain an alphabetized summary listing of those commands, along with the best possible link to each command's manual page.

Conventions Used

In an attempt to make the material in this hypertext as clear as possible for the reader, the following conventions were followed:

spaces are typically represented by whitespace between commands and/or parts of commands
text enclosed within a pair of blue brackets [ ] will indicate the enclosed text (typically commands, arguments, or parameters) is (are) optional
a blue dollar sign ($) will indicate the command line prompt
italicized text enclosed in square brackets, e.g. [Esc] or [Enter] indicates a key press of that key
italicized text enclosed in square brackets such as [Ctrl-c] indicates pressing the Ctrl key while pressing the c key
a blue dollar sign followed by text followed by [Enter], e.g.
```
	 $ ls [Enter]
```
indicates the text is intended to be a command followed by a key press of the Enter key. Note the space preceeding the [Enter] is for clarity.
text on a line with no dollar sign following an [Enter] indicates output from the system resulting from the command on the previous line.
the # character followed by text should be viewed as explanatory comments, not something to type
text (specifically shell commands) enclosed in a rectangular box indicates the contents of a shell program or script. The name of the specific program will also be present within the box (see example).
the button will link you to the next section, while the button will link you to the Table of Contents.
numbered footnotes will typically be links to the footnote text. The footnote text will be located at the end of the section where the footnote reference occurs. The reader can return to the reference of the footnote by using the back button.
in the case where commands are summarized, every attempt will be made to link the command tag to the man page for that command. In some cases, commands do not have their own pages, but are contained in the bash-builtins man page. In that case, once arriving at the builtins man page, one can use their browsers "find" capability to locate the section for that command.

UNIX or Unix?

There was substantial thought put into whether to use the spelling UNIX or Unix when referring to the operating system described and explained in this hypertext. Both spellings of this word are frequently used and often interchanged. Two factors helped guide me to the solution I adopted in this dilemma.

First, the word "UNIX" is a legally registered trademark belonging to The Open Group. A computer operating system can only be referred to as a UNIX system if it has passed The Open Group's rigorous certification program. See additional UN*X legal silliness here [Jargon File 4.4.7]. In contrast, the term Unix is typically used to describe any operating system that is either descended from Bell Laboratories Unix ancestry, or is written as a close imitator of one of its descendants (most notably Linux).

Secondly, according to Dennis Ritchie, "the 'UNIX' spelling originally happened in CACM's 1974 paper The UNIX Time-Sharing System because "we had a new typesetter and troff had just been invented and we were intoxicated by being able to produce small caps." Later, dmr tried to get the spelling changed to 'Unix' in a couple of Bell Labs papers, on the grounds that the word is not acronymic. He failed, and eventually (his words) "wimped out" on the issue. So, while the trademark today is 'UNIX', both capitalizations are grounded in ancient usage." [Jargon File 4.4.6]

Based upon these two factors, I chose to use the term Unix throughout most of this text. Any reference to UNIX herein is a reference to the registered trademark belonging to The Open Group.