Git: Who has modified this line?
Solution 1:
To see commits affecting line 40 of file foo:
git blame -L 40,+1 foo
The +1 means exactly one line. To see changes for lines 40-60, it's:
git blame -L 40,+21 foo
OR
git blame -L 40,60 foo
The second number can be an offset designated with a '+', or a line number. git blame docs
Solution 2:
I'd use the git blame command. That's pretty much exactly what it is for. The documentation should get you started.