Reverse DNS problem - Shell Programming and Scripting

danmero · #4 (**permalink**) 08-26-2008

Quote:

Originally Posted by snake450

Please correct me if i am wrong.

grep '^[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}$' followed by

Your regexp will match anything upto 999.999.999.999

For IPv4 try this awk solution:

Code:

awk -F'.' 'NF==4 && $1 > 0 && $1 && $2 && $3 && $4 <256'

If IP match use the system function to dig your ip and printf to format the output.

Regards,