10.2. Regular Expressions


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A regular expression is a character string that specifies a text search pattern. The search pattern can then be applied to an input string. If a portion of the input string matches the search pattern, the matching portions or designated subparts of it can be extracted.

A regular expression engine is a software library capable of applying search patterns specified in an implementation-dependent regular expression language to arbitrary input strings.

The LOCKSS software uses the Java regular expression engine, but because Java did not always have built-in regular expression support, in some contexts the LOCKSS software uses the older Apache ORO regular expression engine. Typical use of regular expressions in LOCKSS plugins should not result in noticeable differences between the two engines' capabilities.