I can do that in php with the following code:

$dt1 = '2011-11-11 11:11:11';
$t1 = strtotime($dt1);

$dt2 = date('Y-m-d H:00:00');
$t2 = strtotime($dt2);

$tDiff = $t2 - $t1;

$hDiff = round($tDiff/3600);

$hDiff will give me the result in hours.

How do I implement the above in bash shell?

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