Regular Expressions; Table 5: Supported Regular Expression Metacharacters - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - SYSTEM BASICS CONFIGURATION GUIDE 2010-10-04 Configuration Manual

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The filtering is performed before redirection. In the following example, the cnfgfltr.txt file
will contain the output of show config include-defaults beginning with the first occurrence
of the string inter.
host1#show config include-defaults &> cnfgfltr.txt | begin inter

Regular Expressions

A regular expression uses special characters—often referred to as metacharacters—to
define a pattern that is compared with an input string. You can use regular expressions
to filter the output of show commands and to define AS-path access lists and community
lists to more easily filter routes.
For examples of using regular expressions with AS-path access lists and community lists,
see JunosE IP Services Configuration Guide.
Metacharacters
Table 5 on page 39 describes the metacharacters supported for regular expression
pattern-matching.

Table 5: 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.
Chapter 2: Command-Line Interface
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