Well it isn't "grabbing the entire line". It's printing the entire line. But that's because you said it should print that. Try printing $&.

I must say that both your title, and your question are poorly phrased. From your question, it's not at all clear what you want to "grab" if the line contains something else. Do you want to grab up to the second ], regardless what else is on the line? Do you want to "grab" up to the third whitespace character? Are you trying to match IP-numbers between the brackets, or version numbers, or just a bunch of numbers and dots? Or do you want the first 36 characters?

Asking for regexes with no better specification than one example is a waste of everyones time.

Abigail