Specifying URL regular expressions (url_regex)
Entries of type url_regex within the configuration files use regular expressions to perform a match.
The following table offers examples to illustrate how to create a valid url_regex.
| Value | Description |
|---|---|
| x | Matches the character x. |
| . | Match any character. |
| ^ | Specifies beginning of line. |
| $ | Specifies end of line. |
| [xyz] | A character class. In this case, the pattern matches either x, y, or z. |
| [abj-oZ] | A character class with a range. This pattern matches a, b, any letter from j through o, or Z. |
| [^A-Z] | A negated character class. For example, this pattern matches any character except those in the class. |
| r* | Zero or more r’s, where r is any regular expression. |
| r+ | One or more r’s, where r is any regular expression. |
| r? | Zero or one r, where r is any regular expression. |
| r{2,5} | From two to five r’s, where r is any regular expression. |
| r{2,} | Two or more r’s, where r is any regular expression. |
| r{4} | Exactly 4 r’s, where r is any regular expression. |
| "[xyz]\"images" | The literal string [xyz]"images" |
| \X | If X is a, b, f, n, r, t, or v, then the ANSI-C interpretation of \x; Otherwise, a literal X. This is used to escape operators such as *. |
| \0 | A NULL character. |
| \123 | The character with octal value 123. |
| \x2a | The character with hexadecimal value 2a. |
| (r) | Matches an r; where r is any regular expression. You can use parentheses to override precedence. |
| rs | The regular expression r, followed by the regular expression s. |
| r|s | Either an r or an s. |
| #<n># | Inserts an end node causing regular expression matching to stop when reached. The value n is returned. |