grep -rnw '/path/to/somewhere/' -e 'pattern'
- -r or -R is recursive,
- -n is line number, and
- -w stands for match the whole word.
- -l (lower-case L) can be added to just give the file name of matching files.
- -e is the pattern used during the search
grep -Ril "text-to-find-here" /
istands for ignore case (optional in your case).
Rstands for recursive.
lstands for "show the file name, not the result itself".
/stands for starting at the root of your machine.