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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 .


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