9.2 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.
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Match any character (can match newline in gawk).
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*
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Match zero or more preceding elements.
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^
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Match beginning of line or string.
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$
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Match end of line or string.
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\
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Escape following character.
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[ ]
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Match one from a list or range.
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\( \)
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Store pattern for later replay.
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\n
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Reuse matched text stored in nth \( \).
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{ }
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Match a range of instances.
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\{ \}
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Match a range of instances.
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\<
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Match word's beginning.
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\>
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Match word's end.
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+
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Match one or more preceding elements.
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?
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Match zero or one preceding elements.
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Separate choices to match.
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( )
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Group expressions to match.
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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, the
metacharacters in this table apply to the pattern you are searching
for but not to the string replacing it.
In gawk, {
} is specified in the POSIX standard and is supported by
gawk if you run it with the
-Wre-interval option.
In ed, vi, and sed,
the following additional metacharacters are valid only in a
replacement pattern:
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\
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Escape following character.
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\n
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Reuse matched text stored in nth \( \).
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&
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Reuse previous search pattern.
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~
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Reuse previous replacement pattern.
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\e
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Turn off previous \L or \U.
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\E
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Turn off previous \L or \U.
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\l
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Change single following character to lowercase.
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\L
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Change following characters to lowercase until \E is encountered.
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\u
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Change single following character to uppercase.
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\U
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Change following characters to uppercase until \E is encountered.
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