grep and expression with (*,*)

Question

I have included write(*,*) in a large project. Now I want to grep

grep -n 'write(*,*)' response.f

and got nothing found. Why are expressions with parenthesess not suitable for classical grep?

Answer 1

The parentheses aren't the problem, but * is a regex metacharacter. Try grep -nF to not interpret as a regex:

grep -nF 'write(*,*)' response.f

Or, alternatively, escape:

grep -n 'write(\*,\*)' response.f

Your regex was interpreted as "zero or more (, then zero or more ,, then ).