To grep efficiently by upward recursion

Question

How can you run the following in Grep?

grep "TODO" *
grep "TODO" */*
grep "TODO" */*/*
grep "TODO" */*/*/*
grep "TODO" */*/*/*/*

I run unsuccessfully

grep -r "TODO"

I get what I want by ack-grep by ack-grep TODO.

Answer 1

If you want to grep recursively, use -R/-r and a path:

grep -R "TODO" .

So either you're missing the path (.) or I misunderstand your question.

Answer 2

Let the shell do the work:

grep "TODO" **/*

Answer 3

find . -exec grep -H TODO {} +