MX diags .txt Interrogator
You can do basic regex type stuff (search for things) in a diags .txt file.
Like everything else in life it's a good idea to ask the right question
It's javascript so performance will very, very much depend upon your PC / browser / file size.
It has been tried on a 12 meg file / over a million entries, and unsurprisingly the browser farted a bit
Edit: Don't let the next few posts about scary regex put you off - Just type the bit of text you want to find in any entry and click "search"
The entries will be highlighted in GREEN or you can tick "Exclude !" to hide them.
For real regex people, please note.
The search expression is per entry, NOT the file as a whole.