For example i'm having the below contents in a file:
expr is great when you want to split a string into just two parts. The .* also makes expr good for skipping a variable number of words when you don't know how many words a string will have. But expr is lousy for getting, say, the fourth word in a string. And it's almost useless for handling more than one line of text at a time.
I want to find the third letter from each line.