Forums Scripts & Popups [Twitch] How many lines written in chat?

Hey there, I'd like to write a script saying "user" (Name in chat) has been writing "x" amount of lines in the chat when he/she subscribes, how do I do that? I have a file with logs from the chat and me thinking the "script" needs to count how many times "user" appears in the file.

How do I make this work? Any help would be appreciated.