The following typographic conventions are used in this book:
is used for filenames and command names. It is also used to highlight comments in command examples, and to define new terms when they first appear in the text.
is used in examples to show the text that you enter literally, and in regular text to show operators, variables, and the output from commands or programs.
is used in examples to show the user's actual input at the terminal.
is used in examples to show variables for which a context-specific substitution should be made. The variable
filename, for example, would be replaced by some actual filename.
are used to attach parenthetical notes which you should not read on your first reading of this book. Sometimes, lies are presented to simplify the discussion, and a footnote restores the lie to truth. Often, the material in the footnote will be advanced information that is not discussed anywhere else in the book.