[Perl] How can I convert epoch seconds to date format

not sure on what you are exactly trying to do, but for conversions from epoch to localtime you can use 'localtime'

perldoc -f localtime

localtime EXPR
       localtime
               Converts a time as returned by the time function to a 9-element
               list with the time analyzed for the local time zone.  Typically
               used as follows:

                   #  0    1    2     3     4    5     6     7     8
                   ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) =
                                                               localtime(time);

Or you can use one of the many modules that does dateconversions, my current favorite is DateTime.