How to grep files in git repo?

Maybe you want git ls-files which lists the files in the index? (and automatically adjusts for your current directory inside the git work directory)

I think git ls-files will do the trick for you.

So:

 git ls-files "*middleware*"

You might consider a non-git solution in this case.

find itself has the ability to do what you want in a more efficient manner than piping its results into grep:

find . -name 'middleware*'

You will need to quote the pattern so that the * isn't expanded by the shell before being passed to find.

There is a powerful program called ack that is, well, better than grep, and one of my favorite uses for ack is exactly what you've mentioned -- finding files that match a pattern within a tree. ack uses perl regexps, not shell fileglobs, though.

ack -g middleware

If you want to search within those files, ack lets you do that more easily than writing a shell loop over the results of find that greps within each file. Compare the two and see which one you prefer:

for f in $(find . -name 'middleware*')do    grep 'pattern in file' $fdone

versus

ack -G 'middleware' 'pattern in file'

I highly recommend ack as something to add to your toolkit.