# grep -o '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}' file.txt
# grep -E -o '(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)' file.txt
#perl -n '/(\d+\.\d+\.\d+\.\d+)/ && print "$1\n"' < file
for i in `cat host2.txt`
do
host $i
done
REFERENCES http://stackoverflow.com/questions/427979/how-do-you-extract-ip-addresses-from-files-using-a-regex-in-a-linux-shell
