Section 6.2. Metacharacters, Listed by Unix Program

6.2. Metacharacters, Listed by Unix Program

Some metacharacters are valid for one program but not for another. Those that are available to a Unix program are marked by a checkmark (x) in Table 6-1. Items marked with a P are specified by POSIX; double-check your system's version. Full descriptions are provided after the table.

Table 6-1. Unix metacharacters

Symbol	ed	ex	vi	sed	awk	grep	egrep	Action
.								Match any character.
*								Match zero or more preceding .
^								Match beginning of line/string.
$								Match end of line/string.
\								Escape following character.
[ ]								Match one from a set.
( \)								Store pattern for later replay. a
\n								Replay subpattern in match.
{ }					P		P	Match a range of instances.
\{ \}								Match a range of instances.
\< \>								Match word's beginning or end.
+								Match one or more preceding.
?								Match zero or one preceding.
								Separate choices to match.
( )					]			Group expressions to match.
a Stored subpatterns can be replayed during matching. See Table 6-2.

Note that in ed , ex , vi , and sed , you specify both a search pattern (on the left) and a replacement pattern (on the right). The metacharacters in Table 6-1 are meaningful only in a search pattern.

In ed , ex , vi , and sed , the metacharacters in Table 6-2 are valid only in a replacement pattern.

Table 6-2. Metacharacters in replacement patterns

Symbol	ex	vi	sed	ed	Action
\				]	Escape following character.
\ n			]		Text matching pattern stored in \ ( \ ).
&					Text matching search pattern.
~					Reuse previous replacement pattern.
%					Reuse previous replacement pattern.
\u \U					Change character(s) to uppercase.
\l \L					Change character(s) to lowercase.
\E					Turn off previous \U or \L .
\e					Turn off previous \u or \l .