The ability to search for (regular) expressions, and not just words or
substrings is a powerful feature, but most users will not be able to
master the creation of such expressions.
- Regular expressions are useful for allowing alternatives, such as
"index[ -]databases" to denote that there may be a space or hyphen between
the words, or "absor[bp]" for a choice between "b" and "p".
- The agrep library allows not only regular expressions
but a parameter to allow a number of exceptions (possible typos).
- To complicate matters there are many different syntaxes for regular
expressions. The GNU regex library supports most of them.
The Fish-Search is one of the few
tools that offer a choice between all these syntaxes.
