tl: dr:
grep -rIL searchword
De acordo com o Manual :
-R, -r, --recursive
Read all files under each directory, recursively; this is equivalent to the -d recurse option.
-L, --files-without-match
Suppress normal output; instead print the name of each input file from which no output would normally have been printed. The scanning will stop on the first match.
-I
Process a binary file as if it did not contain matching data; this is equivalent to the --binary-files=without-match option.