Regular expression operators:
| Comparison | Operator |
|---|---|
| regular expression | ~ |
| regular expression, case-insensitive | ~* |
| not equal to regular expression | !~ |
| not equal to regular expression, case-insensitive | !~* |
Regular expression special characters:
| Test | Special Characters |
|---|---|
| start | ^ |
| end | $ |
| any single character | . |
| set of characters | [ccc] |
| set of characters not equal | [^ccc] |
| range of characters | [c-c] |
| range of characters not equal | [^c-c] |
| zero or one of previous character | ? |
| zero or multiple of previous characters | * |
| one or multiple of previous characters | + |
| OR operator | | |
Note that the caret (^) has
a different meaning outside and inside square brackets ([]).
Use of a backslash to mask special characters. For example, to test for a dollar sign, use \$. To test for an asterisk, use \*. To test for a literal backslash, use two backslashes (\\).
Examples of regular expressions
| Test | Operation |
|---|---|
| begins with D | ~ '^D' |
| contains D | ~ 'D' |
| D in second position | ~ '^.D' |
| begins with D and contains e | ~ '^D.*e' |
| begins with D, contains e, and then f | ~ '^D.*e.*f' |
| contains A, B, C, or D | ~ '[A-D]' or ~ '[ABCD]' |
| contains A or a | ~* 'a' or ~ '[Aa]' |
| does not contain D | !~ 'D' |
| does not begin with D | !~ '^D' or ~ '^[^D]' |
| begins with D, with one optional leading space | ~ '^ ?D' |
| begins with D , with optional leading spaces | ~ '^ *D' |
| begins with D, with at least one leading space | ~ '^ +D' |
| ends with G, with optional trailing spaces | ~ 'G *$' |
Example: