I've a script which produces the following output:

subnet,prefix,name
10.0.0.0,30,Site ABC
10.0.0.4,30,ISDN dial-up for Ex House
10.0.0.8,30,
10.0.0.12,30,P2P link

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Before printing the output, I would like to check if the "name" field is undef and if so, set a value. The data is in a hash, and when I dump out the values, I think this is a hash of hashes:

$VAR1 = {
          '10.0.0.0,30' => {
                             'comment' => 'Site ABC',
                             'ipn' => 167772160,
                             'maskn' => 4294967292
                           },
          '10.0.0.4,30' => {
                             'comment' => 'ISDN dial-up for Ex House',
                             'ipn' => 167772164,
                             'maskn' => 4294967292
                           },
          '10.0.0.8,30' => {
                             'comment' => undef,
                             'ipn' => 167772168,
                             'maskn' => 4294967292
                           },
          '10.0.0.12,30' => {
                              'comment' => 'P2P link',
                              'ipn' => 167772172,
                              'maskn' => 4294967292
                            },

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So, I think i need to iterate over the outer hash and then check if the value for 'comment' in the inner hash is undef; if it is, then set it. I have struggled to work out how to use the comment key in the inner hash, I came up with the following, but it doesn't work (the data is in %subnets):

foreach my $ip ( keys %subnets ) {
    if (undef $subnets{$ip}{$comment}) {
        $subnets{$ip}{$comment} = 'ALLOCATED';
    }
}

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Where did I go wrong?!

In reply to Check/set hash of hashes value by stroke

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