Switching your Linux systems to the new DST

From now on, instead of DST starting on the first Sunday in April, it starts on the second Sunday of March. (This year, that's March 11.) Come Fall, Daylight Savings will end on the first Sunday in November -- November 4, this year -- instead of the last Sunday of October. That means one big mess for many pre-2005 programs and operating systems, which have the old April/October DST rules hardwired into them.

Now, unlike Windows, Linux and the rest of the Unix operating system family don't have Daylight Savings Time innately. Instead, they use an entirely different way of telling time.

Most Linux systems have two clocks. The hardware clock, a.k.a. the "CMOS clock," is present in most x86-based systems. The CMOS, a battery-backed time clock located on the motherboard, runs 24/7. The system clock, on the other hand, starts when you boot up your system. This is the clock used by most internal Linux programs and Linux applications.

By default, the system clock takes its cue from the CMOS. A far better way to set up the system clock, if you have an Internet connection (and who doesn't?), is to use a program like ntpd. This program uses the NTP (network time protocol) to obtain the correct time from an NTS (network time server).

Some older Linux and Unix systems required you to use a program called ntpdate to actually set the time manually. Now, that functionality is included in the ntpd package.