The following typographic conventions are used in this book:
Used for names, including pathnames, filenames, program and command
names, usernames, hostnames, machine names, and mailing-list names,
as well as for mail addresses. It also is used to indicate that part
of a program’s output is not specific. For example,
error: number or
file" indicates that the error will be
shown either as a number or as a filename. Italic is also used to
emphasize new terms and concepts when they are introduced.
Used in examples to show the contents of files or the output from
commands. This includes examples from the configuration file or other
files such as message files, shell scripts, or C-language program
source. Constant-width text is quoted only when necessary to show
enclosed space; for example, the five-character
From " header.
Single characters, symbolic expressions, and command-line switches
are always shown in constant-width font. For instance, the
o option illustrates a single character, the rule
$- illustrates a symbolic expression, and
-d illustrates a command-line switch.
Used in examples to show commands or some other text that is to be
typed literally by the user. For example, the phrase
/var/run/sendmail.pid means the user should type
“cat /var/run/sendmail.pid” exactly
as it appears in the text or example.
Used in examples to show variables for which a context-specific
substitution should be or will be made. In the string
num, for example,
num will be a user-assigned integer.
Indicates a user shell.
Indicates a root shell.