Using regular expressions you can define a pattern to match a multi-character pattern. For example, you can write a regular expression to match all hosts whose names contain Host and are followed by exactly two digits. That means you want to match the following strings:
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The expression that matches this pattern is: Host[0-9][0-9].
Going further, you can write an expression that matches all hosts whose names contain Host, followed by exactly two digits, and optionally a lowercase letter. That means you want to match the following strings:
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The expression that matches this pattern is: Host[0-9][0-9][a-z]?.
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The plus sign ‘+’ means one or more times. For example, case[0-9]+ matches case1, case12345, but not simply case. |
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{3} occur exactly three times. |
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{2,4} occur at least two times and as many as four times. |
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{3,} occur at least three times up to infinity. |
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The caret ‘^’ reverses the meaning of a regular expression element. For example, [^KLM] matches a single character that is not K, L, or M. |
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A backslash ‘\’ followed by a lowercase ‘d’, \d, means a digit. |
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A backslash ‘\’ followed by a lowercase ‘w’, \w, means a word character (an alphanumeric character or an underscore ‘_’). It has the same meaning as [a-zA-Z_0-9]. |
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A backslash ‘\’ followed by a lowercase ‘s’, \s, means a white space character. It has the same meaning as [\t\n\x0b\r\f]. |
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Two backslashes “\\” followed by a period ‘.’, \\., means a literal dot. |
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The flag (?i) makes the regular expression case insensitive. In Foglight for Infrastructure, the Add OS Monitor wizard uses this flag in the Resource Mapping regular expression. For example: (?i).*host.*. |
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The flag (?x) allows you to add comments to explain a complex or unusual pattern. The comment starts with a number sign ‘#’. For example: (?x)[KLM]:.* # We dislike drives K through M. |
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