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Metacharacters

Table 6 describes the metacharacters supported for regular expression pattern-matching.

Table 6: Supported Regular Expression Metacharacters

Metacharacter

Description

^

Matches the beginning of the input string.

Alternatively, when used as the first character within brackets—[^ ]—matches any number except the ones specified within the brackets.

$

Matches the end of the input string.

.

Matches any single character, including white space.

*

Matches 0 or more sequences of the immediately previous character or pattern.

+

Matches 1 or more sequences of the immediately previous character or pattern.

?

Matches 0 or 1 sequence of the immediately previous character or pattern.

()

Specifies patterns for multiple use when followed by one of the multiplier metacharacters: asterisk *, plus sign +, or question mark ?

[ ]

Matches any enclosed character; specifies a range of single characters.

– (hyphen)

Used within brackets to specify a range of AS or community numbers.

_ (underscore)

Matches a ^, a $, a comma, a space, a {, or a }. Placed on either side of a string to specify a literal and disallow substring matching. Numerals enclosed by underscores can be preceded or followed by any of the characters listed above.

|

Matches characters on either side of the metacharacter; logical OR.


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