Shell Programming and Scripting

awk -F\. '{print $(NF-1) FS $NF}' file

# assume url is first field; change if needed
awk '
        {
                gsub( "^.*://", "", $1 );      # ditch the http://  ftp:// etc
                n = split( $1, a, "." );
                if( length( a[n] ) == 2 )       # assuming all two character top level domains are country codes
                        printf( "%s.%s.%s\n", a[n-2], a[n-1], a[n] );
                else
                        printf( "%s.%s\n",  a[n-1], a[n] );
        }
' list-file-name

http://foo.com

#!/bin/bash
exec 6<"myfile"
while read -r LINE<&6
do
   LINE=${LINE/www./}
   IFS="."
   LINE=(${LINE/http:\/\/})
   want="${LINE[@]:1}"
   echo "${want// /.}"
done
exec 6<&-