Introduction to Searching with Regular Expressions
  The explosive rate of information growth and availability often makes it increasingly difficult to locate information pertinent to your needs. These problems are often compounded when keyword based search methodologies are not adequate for describing the information you seek. In many instances, information such as Web site URLs, phone numbers, etc. can often be better identified through the use of a textual pattern than by keyword. For example, many more phone numbers could be picked up by a search for the pattern (XXX) XXX-XXXX, where X could be any digit, than would be by a search for any specific phone number (i.e. the keyword approach). Programming languages typically allow for the matching of textual patterns via the usage of regular expressions. This tutorial will provide an introduction to the basics of programming regular expressions as well as provide an introduction to how regular expressions can be applied to data processing tasks such as information extraction and search refinement. 
Christopher M. Frenz