use Date::Manip;
Date_Init("TZ=PST");

##</code><code>##


       Unable to determine TimeZone
           Perhaps the most common problem occurs when you get
           the error:

              Error: Date::Manip unable to determine TimeZone.

           Date::Manip tries hard to determine the local time-
           zone, but on some machines, it cannot do this (espe-
           cially non-unix systems).  To fix this, just set the
           TZ variable, either at the top of the Manip.pm file,
           or in the DateManip.cnf file.  I suggest using the
           form "EST5EDT" so you don't have to change it every 6
           months when going to or from daylight savings time.
           Windows NT does not seem to set the TimeZone by
           default.  From the Perl-Win32-Users mailing list:

              > How do I get the TimeZone on my NT?
              >
              >      $time_zone = $ENV{'TZ'};
              >
              You have to set the variable before, WinNT doesn't set it by
              default.  Open the properties of "My Computer" and set a SYSTEM
              variable TZ to your timezone.   Jenda@Krynicky.cz

           This might help out some NT users.