=head1 Info

 Script to search text for ip address on a given subnet
 Subnet can be specified as x.x.x.x/x.x.x.x or x.x.x.x/xx
 Options are similar to grep:
     -c count matching lines
     -v select lines which do not match
     -f <pattern file> containing one subnet in the form above per line
 Example: ./subnet-grep.pl 10.5.1.0/24 /etc/hosts
 Example: ./subnet-grep.pl -c 192.168.1.0/255.255.255.0 input1.txt input2.txt

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