Linux in a Nutshell, Fourth Edition

Metacharacters, Listed by Linux Program

Some metacharacters are valid for one program but not for another. Those available to a given program are marked by a checkmark (✓) in the following table. Notes are provided after the table, and full descriptions of metacharacters are in the following section.

Symbol	ed	vi	sed	gawk	grep	egrep	Action
.	✓	✓	✓	✓	✓	✓	Match any character (can match newline in gawk).
*	✓	✓	✓	✓	✓	✓	Match zero or more preceding elements.
^	✓	✓	✓	✓	✓	✓	Match beginning of line or string.
$	✓	✓	✓	✓	✓	✓	Match end of line or string.
\	✓	✓	✓	✓	✓	✓	Escape following character.
[ ]	✓	✓	✓	✓	✓	✓	Match one from a list or range.
\( \)	✓	✓	✓				Store pattern for later replay.
\ n	✓	✓	✓				Reuse matched text stored in nth \( \).
{ }				✓			Match a range of instances.
\{ \}	✓	✓	✓		✓		Match a range of instances.
\<		✓					Match word’s beginning.
\>		✓					Match word’s end.
+				✓	✓	✓	Match one or more preceding elements.
?				✓	✓	✓	Match zero or one preceding elements.
|				✓		✓	Separate choices to match.
( )				✓		✓	Group expressions to match.

On some Linux systems, grep is a link to egrep, so whenever you run grep you actually get egrep behavior.

In ed, vi, and sed, when you perform a search-and-replace (substitute) operation, ...