open FILE, "<", "$hostfile" || die "Cannot open $hostfile $!";

[download]

You shouldn't quote variables like that:

What's wrong with always quoting "$vars"?

The high precedence of the || operator means that die will only execute if $hostfile contains the string "" or the string "0".    You need to either use parentheses with open: 

open( FILE, "<", $hostfile ) || die "Cannot open $hostfile $!";

[download]

Or use the low precedence or operator: 

open FILE, "<", $hostfile or die "Cannot open $hostfile $!";

[download]


while (<FILE>) {
    chomp;
    my ($key, $value) = split (" ", $_);
    $hosts{$key} = $hosts{$value};
    }

[download]

That should probably be: 

while (<FILE>) {
    my ($key, $value) = split;
    $hosts{$key} = $value;
    }

[download]

Or if you want all the hosts associated with each IP address: 

while (<FILE>) {
    my ($key, @values) = split;
    push @{$hosts{$key}} = @values;
    }

[download]

In reply to Re: How To Read Hosts File Into a Hash by jwkrahn
in thread How To Read Hosts File Into a Hash by at2marty

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