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 bullet () in Table 6.1. Items marked with a "P" are specified by POSIX; double-check your system's version. (On Solaris, the versions in /usr/xpg4/bin accept these items.) 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.[1]
\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.

[1] 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.