# This isn't perlish at all but if you need a faithfull emulation...
my $date = `date '+%m%d%y'|sed s/\ /_/g`;
chomp($date);

print "checking the existence of log";
if (-e "/local/home/admin/log${date}_box_50")
{
    rename "/local/home/admin/temp_log_copy",  "/local/home/admin/log${date}_box_50a"
	or die "Failed to rename";
} else {
    rename "/local/home/admin/temp_log_copy",  "/local/home/admin/log${date}_box_50"
	or die "Failed to rename";
}