Checks if the input is looks like an IP address

valid_ip.sh

#!/bin/bash
valid_ip(){ # (ip)
	local INVALID=0
	grep -Eq '^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$' <<< "$1" || INVALID=1
	for N in $(echo "$1" | tr '.' ' '); do
		test "$N" -gt 255 && INVALID=1;
	done
	return "$INVALID"
}