I'm building a log parser app using ruby on rails. I'm looking for a free regex generator than is able to produce the regex expression of a specific part of a log file entry. I'm wondering if there's a regex tool out there that allows the user to highlight certain parts of a log file entry and generates the regex expression for it. Thanks in advance.

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I use https://regex101.com/. It's not quite as automated as you are asking for but it's the best I've found so far - I only periodically have to delve into regex, so I never build up any momentum and always need some hand-holding, and this site is the one I currently use.

The tool you are after may not exist.... if you highlight certain text, in many cases, there are multiple expressions that can return the same result. So the best/the easiest way is to provide a sample of your base text and then build expressions and see how they interact with your samples, which is exactly as this site and many others do.

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