Parentheses For Recall - Cisco Catalyst 6500 Series Command Reference Manual

Chapter 1 Command-Line Interface
Using the CLI String Search
For example,
_1300_
matches any string that has 1300 somewhere in the string. The string's 1300 can be preceded by or end
with a space, brace, comma, or underscore. For example,
{1300_
matches the regular expression, but 21300 and 13000 do not.
Using the underscore character, you can replace long regular expression lists, such as the following:
^1300$ ^1300(space) (space)1300 {1300, ,1300, {1300} ,1300, (1300
with
_1300_

Parentheses for Recall

As shown in the "Multipliers" section on page 1-9, you use parentheses with multiple-character regular
expressions to multiply the occurrence of a pattern. You can also use parentheses around a single- or
multiple-character pattern to remember a pattern for use elsewhere in the regular expression.
To create a regular expression that recalls a previous pattern, you use parentheses to indicate a
remembered specific pattern and a backslash (\) followed by an integer to reuse the remembered pattern.
The integer specifies the occurrence of the parentheses in the regular expression pattern. If you have
more than one remembered pattern in your regular expression, then \1 indicates the first remembered
pattern, \2 indicates the second remembered pattern, and so on.
This regular expression uses parentheses for recall:
a(.)bc(.)\1\2
This regular expression matches an a followed by any character (call it character 1), followed by bc,
followed by any character (character 2), followed by character 1 again, and then followed by character 2
again. The regular expression can match aZbcTZT. The software remembers that character 1 is Z and
character 2 is T and then uses Z and T again later in the regular expression.
Catalyst 6500 Series Switch SSL Services Module Command Reference
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