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Syntax Used in VPO Configuration Files
Syntax for Message Pattern Matching
Appendix A290
Syntax for Message Pattern Matching
Table A-2 shows the components of the VPO pattern-matching language
that can be used to write expressions to match incoming messages. You
can combine individual components to form complex patterns.
Table A-2 VPO Pattern Matching Language
Component Description
Ordinary
Characters
Ordinary characters are expressions that represent themselves. Any
character of the supported character set can be used.
However, if any of the following special characters are used:
[ ] < > | ˆ $
they must be prefaced with a backslash ( \ ) to mask their usual function.
If ˆ and $ are not used as Anchoring Characters, they are considered as
ordinary characters.
The Mask
Character
Use the backslash ( \ ) to mask the special meaning of the characters:
[ ] < > | ˆ $
A special character preceded by \ results in an expression that matches
the special character itself.
Note that because ˆ and $ only have special meaning when placed at the
beginning and end of a pattern respectively, you need not mask them when
they are used within a pattern (in other words, not at beginning or end).
The only exception is the tab character, that is specified by entering /t in
the pattern string.
Expression
Anchoring
If the caret (ˆ) is used as the first character of the pattern, only expressions
discovered at the beginning of lines are matched. For example, “ˆab”
matches the string “ab” in the line “abcde”, but not in the line “xabcde”.
If the dollar sign is used as the last character of a pattern, only expressions
at the end of lines are matched. For example, de$ matches de in the line
abcde, but not in the line abcdex.