Key
The name of a keyboard key.
Return
and
Enter
both refer to
the same key.
Term
The defined use of an important word or phrase.
User input
Commands and other text that you type.
Variable
or
Replaceable
The name of a placeholder in a command, function, or other
syntax display that you replace with an actual value.
-chars
One or more grouped command options, such as
-ikx
. The
chars are usually a string of literal characters that each
represent a specific option. For example, the entry
-ikx
is
equivalent to the individual options
-i
,
-k
, and
-x
. The plus
character (
+
) is sometimes used as an option prefix.
-word
A single command option, such as
-help
. The word is a
literal keyword. The difference from -chars is usually obvious
and is clarified in an Options description. The plus character
(
+
) and the double hyphen (
--
) are sometimes used as option
prefixes.
[ ]
The bracket metacharacters enclose optional content. If the
contents are a list separated by |, you choose one of the
items.
{ }
The brace metacharacters enclose required content. If the
contents are a list separated by |, you must choose one of
the items.
...
The preceding element can be repeated an arbitrary number
of times. Ellipsis is sometimes used to indicate omitted items
in a range.
Indicates the continuation of a code example.
|
Separates items in a list of choices.
WARNING
A warning calls attention to important information that if not
understood or followed will result in personal injury or
nonrecoverable system problems.
CAUTION
A caution calls attention to important information that if not
understood or followed will result in data loss, data corruption,
or damage to hardware or software.
IMPORTANT
This alert provides essential information to explain a concept
or to complete a task.
NOTE
A note contains additional information to emphasize or
supplement important points of the main text.
Examples and Shells
This document describes practices used by the system administrator. Since the
root
user (superuser)
is required to use the POSIX shell
/sbin/sh
, all command examples use that shell. The POSIX
shell is defined in sh-posix(1). For information on other shells, see the Shells User’s Guide and
sh(1).
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Support and Other Resources
