Extract IP address from string using grep
From ben.goodacre.name/tech
-o option tells grep to only print the parts that match the grep
$ host yahoo.com | grep -Eo '([0-9]{1,3}\.){3}[0-9]{1,3}'
209.191.122.70
67.195.160.76
69.147.125.65
72.30.2.43
98.137.149.56
