Manually assign a value when inet_ntoa does return an ip address

Question

Code:

foreach $hostname (@hostnameUniqueSorted){
    $ipaddr = inet_ntoa((gethostbyname($hostname))[4]);
    if(chomp($ipaddr) =~ '^$') $ipaddr == "ip not avail";   <-- doesn't work
}

If the host doesn't return an IP address, it would break and show:

Usage: Socket::inet_ntoa(ip_address_sv) at ./abc line 24.

How do I catch it and assign maybe 'ip not avail' for the $ipaddr?

I added the last line but it doesn't work.

Answer 1

You should be checking the return value of gethostbyname - it returns an empty list if the host is not found, and inet_ntoa can't deal with that.

Try something like the following:

foreach my $hostname (@hostnameUniqueSorted) {
    my @host = gethostbyname($hostname);
    if (scalar(@host) == 0) {
        $ipaddr = "not found";
    } else {
        $ipaddr = inet_ntoa($host[4]);
    }
    print $hostname, " => ", $ipaddr, "\n";
}

_{Note that your syntax is incorrect, {} are necessary after the if condition. And I don't believe chomp returns anything, so that test invalid. (And == is for comparison only, not assignment.)}