explainshell.com - grep.1posix -oP %27%5Cd%2B%5C.%5Cd%2B%5C.%5Cd%2B%5C.%5Cd%2B%28%5C%2F.%5Cd%2B%7C%29%27 file_with

-oP %27%5Cd%2B%5C.%5Cd%2B%5C.%5Cd%2B%5C.%5Cd%2B%28%5C%2F.%5Cd%2B%7C%29%27 file_with_ips

search a file for a pattern

source manpages: grep