This book uses conventions to make its explanations shorter and clearer. The following paragraphs describe these conventions.
Mac OS X
The term Mac OS X refers to both Mac OS X and Mac OS X Server. Important differences between the two are noted.
Mac OS X versions
This book is based on Mac OS X 10.4. Significant differences between versions 10.3 and 10.4 are noted. Because the book focuses on the underlying UNIX operating system, which changes little from one release of OS X to the next, the text will remain relevant through several future releases. The author's Web site (www.sobell.com) provides corrections and updates as appropriate.
Text and examples
The text is set in this type, whereas examples are shown in a monospaced font (also called a fixed-width font):
$ cat practice This is a small file I created with a text editor.
The next paragraph explains why part of the first line is in a bold typeface.
Items you enter
Everything you enter at the keyboard is shown in a bold typeface: Within the text, this bold typeface is used; within examples and screens, this one is used. In the previous example, the dollar sign ($) on the first line is a prompt that OS X displays, so it is not bold; the remainder of the first line is entered by a user, so it is bold.
Names of utilities are printed in this bold sans serif typeface. This book references the emacs editor and the ls utility or ls command (or just ls) but instructs you to enter ls a on the command line. In this way the text distinguishes between utilities, which are programs, and the instructions you give on the command line to invoke the utilities.
Filenames appear in a bold typeface. Examples are memo5, letter.1283, and reports. Filenames may include uppercase and lowercase letters; however, Mac OS X can be case sensitive (page 925), so memo5, MEMO5, and Memo5 may name three different files. By default these three filenames refer to the same file. For more information refer to "Filenames" on page 74.
Within the text, characters and character strings are marked by putting them in a bold typeface. This convention avoids the need for quotation marks or other delimiters before and after a string. An example is the following string, which is displayed by the passwd utility: Mismatch; try again, EOF to quit.
Buttons and labels
Words appear in a bold typeface in the sections of the book that describe a GUI. This font indicates that you can click a mouse button when the mouse pointer is over these words on the screen or over a button with this name.
Keys and characters
This book uses SMALL CAPS for three kinds of items:
Prompts and RETURNs
Most examples include the shell promptthe signal that Mac OS X is waiting for a commandas a dollar sign ($) or sometimes a percent sign (%). The prompt is not in boldface because you do not enter it. Do not type the prompt on the keyboard when you are experimenting with examples from this book. If you do, the examples will not work.
Examples omit the RETURN keystroke that you must use to execute them. An example of a command line is
$ vim memo.1204
To use this example as a model for running the vim editor, give the command vim memo.1204 and press the RETURN key. (Press ESCAPE ZZ to exit from vim; see page 147 for a vim tutorial.) This method of entering commands makes the examples in the book correspond to what appears on your screen.
All glossary entries marked with FOLDOC are courtesy of Denis Howe, editor of the Free Online Dictionary of Computing (www.foldoc.org), and are used with permission. This site is an ongoing work containing definitions, anecdotes, and trivia.
URLs (Web addresses)
Web addresses, or URLs, have an implicit http:// prefix, unless ftp:// or https:// is shown. You do not normally need to specify a prefix when the prefix is http:// but you must use a prefix from a browser when you specify an FTP or secure HTTP site. Thus you can specify a URL in a browser exactly as shown in this book.
Tip, caution, and security boxes
The following boxes highlight information that may be helpful while you are using or maintaining a Mac OS X system.
Tip: This is a tip box
A tip box may help you avoid repeating a common mistake or may point toward additional information.
Caution: This box warns you about something
A caution box warns you about a potential pitfall.
Security: This box marks a security note
A security box highlights a potential security issue. These notes are usually for system maintainers, but some apply to all users.