Suppose you have a 100 files in a directory and you need to find out if a keyword occurs in these files. How would you do it in Unix? How would you do

Suppose you have a 100 files in a directory and you need to find out if a keyword occurs in these files. How would you do it in Unix? How would you do it in Windows?
on Unix:
grep (keyword) (file location & pattern)
grep apple *

on windows:
find (file location & pattern) (keyword)
find . -name 'my*'

How would you handle the above situation if say you had 10 million files?
you could run grep as a background process and output the results to a file for later viewing