| Regular Expressions
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Regular expressions (REs), unlike simple queries, allow you to search for text which matches a particular pattern. |
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< < | REs are similar to (but more poweful than) the "wildcards" used in the command-line interfaces found in operating systems such as Unix and MS-DOS. REs are used by sophisticated search engines, as well as by many Unix-based languages and tools ( e.g., awk , grep , lex , perl , and sed ). |
> > | REs are similar to (but more powerful than) the "wildcards" used in the command-line interfaces found in operating systems such as Unix and MS-DOS. REs are used by sophisticated search engines, as well as by many Unix-based languages and tools ( e.g., awk , grep , lex , perl , and sed ). |
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Examples |
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< < |
compan(y|ies) |
Search for company, companies |
(peter|paul) |
Search for peter, paul |
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> > |
compan(y|ies) |
Search for company, companies |
(peter|paul) |
Search for peter, paul |
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bug* |
Search for bug, bugg, buggg or simply bu (a star matches zero or more instances of the previous character) |
bug.* |
Search for bug, bugs, bugfix (a dot-star matches zero or more instances of any character) |
[Bb]ag |
Search for Bag, bag |
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