Conventions Used in This Book
We use both typography and common Unix documentation conventions to give you additional information in the text.
Typographic Conventions
-
-
Plain text
-
Indicates menu titles, menu options, menu
buttons
, and keyboard accelerators (such as Alt and Ctrl).
-
-
Italic
-
Indicates new or technical terms, system calls, URLs, hostnames, email addresses, filenames, file extensions, pathnames, and directories.
-
-
Constant width
-
Indicates commands, options, switches,
variables
, attributes, keys, functions, types, objects, HTML tags, macros, the contents of files, or the output from commands.
-
-
Constant width bold
-
Shows commands or other text that should be typed literally by the
user
.
-
-
Constant width italic
-
Shows text that should be
replaced
with
user-supplied
values.
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This icon signifies a tip, suggestion, or general note.
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This icon indicates a warning or caution.
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There are times when it is very important to pay attention to the typography because it distinguishes between two similarly named, but different concepts. For example, the
host
command and the
/etc/
hosts
file, or the
jail(2)
system call versus the
jail(8)
command. Sometimes the typeface is an important clue to help you remember which one we're referring to in a given context.
Conventions in Examples
You will see two different prompts in the examples we give for running commands. We follow the time-honored Unix convention of using
%
to represent a non-root shell (e.g., one running as your normal user ID) and
#
to represent a root-equivalent shell. Commands that appear after a
%
prompt can (and probably should) be run by an
unprivileged
user. Commands that appear after a
#
prompt must be run with root privileges. Example P-1 shows three different commands that
illustrate
this point.
Example P-1. Several commands with different prompts
%
ls -lo /var/log
%
sudo ifconfig lo0 127.0.0.2 netmask 255.255.255.255
#
shutdown -r now
The
ls
command runs as a normal user. The
ifconfig
command runs as root, but only because a normal user uses
sudo
to elevate his privileges momentarily (
sudo
is discussed in detail in Chapter 4). The last command shows the
#
prompt,
assuming
that you have already become root somehow before executing the
shutdown
command.
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