Metacharacters, Listed by Unix Program (UNIX in a Nutshell: System V Edition)

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	awk	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.[7]
`\``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.

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.