Pull emails or URLs out of logs: try the regex in a tester first

Logs lie in small ways: plus-addresses, URLs with ports, two addresses on one line. A pattern that “looks right” in the IDE fails on the full file.

Paste 20–50 real lines into Regex Tester. Edit the pattern, watch highlights. Cheaper than redeploying a log job for every typo.

You don’t need RFC-perfect email. Cover your company domains and the messy addresses you actually see. Too strict misses; too loose eats filenames.

For URLs, decide if query strings matter. If you only want host + path, don’t swallow ?utm= unless you mean to. Use groups so you capture only what the next step needs.

Run Text Dedup on the extracted list. Diff against the old script’s output. Keep flags (case, multiline) aligned with the engine you’ll run — JS and Python disagree in places.

The tester runs on your paste locally. Redact production secrets before any sample leaves your machine.