grep output to show only matching file
grep -l
(That's a lowercase L)
You can use the Unix-style -l switch – typically terse and cryptic – or the equivalent --files-with-matches – longer and more readable.
The output of grep --help is not easy to read, but it's there:
-l, --files-with-matches print only names of FILEs containing matches
-l (that's a lower-case L).
Also remember one thing. Very important
You have to specify the command something like this to be more precise
grep -l "pattern" *