-r searches directories recursively instead of single files; -n displays line numbers; -I ignores binary files. -A, -B, -C, and -l set how much context is shown

-r searches directories recursively instead of single files; -n displays line numbers; -I ignores binary files. -A, -B, -C, and -l set how much context is shown: 5 lines of content before the match, after the match, or both; or just the filename and no content.