I agree with all the other comments. Just one note on using Data::Dumper. If you pass it a reference, you'll get more readable output. Your code produces:

$VAR1 = 'name';
$VAR2 = 'alex';
$VAR3 = 'age';
$VAR4 = '20';
$VAR5 = 'sex';
$VAR6 = 'm';
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If you just passed Dumper() a reference, like this:

print Dumper \%hash_init;
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You'll get this:

$VAR1 = {
          'name' => 'alex',
          'age' => '20',
          'sex' => 'm'
        };
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Which is a whole lot nicer to look at.