Tools for generating regular expressions


Deriving regular expressions based on existing text fragments and patterns helps to analyze and recognize similarities in more complex patterns. The tools I tested work well but not always without error. Some tools generated regular expressions that were more generic than they actually should be based on the text fragments, resulting in searches that returned more matches than desired. In particular, these tools may include results that don't actually match the search patterns, resulting in false positives and some fuzziness.

Regular expressions are complex, inherently mapping a fragment and pattern differently. The performance of these tools does deserve credit given the complexity of the tasks. For these generators to be more useful in the future, increased precision would be desirable.


The author would like to thank Axel Beckert and Arne Wichmann for their help and critical comments during the preparation of this article.

The Author

Frank Hofmann works on the road – preferably from Berlin, Geneva, and Cape Town – as a developer, trainer, and author. He is also a co-author of the Debian Package Management book (

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