print scalar(localtime),"\n";
{
   local $ENV{'TZ'} = 'AST4ADT';
   print scalar(localtime),"\n";
}
print scalar(localtime),"\n";

__END__
output
======
Mon Sep 27 15:43:45 2004
Mon Sep 27 16:43:45 2004
Mon Sep 27 15:43:45 2004