The Clock Mini-HOWTO

Ron Bean, [email protected]

1. Introduction

• 1.1 Does Anybody Really Know What Time It Is?
• 1.2 Where to Find Stuff: "The Usual Places"
• 1.3 Acknowledgements

2. How Linux Keeps Track of Time

• 2.1 Basic Strategies
• 2.2 Potential Conflicts
• 2.3 Should the RTC use Local Time or UTC, and What About DST?
• 2.4 How Linux keeps Track of Time Zones
• 2.5 The Bottom Line

3. Software

• 3.1 Clock(8) and Hwclock(8)
• 3.2 Adjtimex(8)
• 3.3 Xntpd and ntpd: the Network Time Protocol
• 3.4 Chrony
• 3.5 Clockspeed

4. Radio Clocks

• 4.1 CHU and the "Gadget Box"
• 4.2 WWV and the "Most Accurate Clock"
• 4.3 GPS and the "Totally Accurate Clock"
• 4.4 Low-frequency Time Signals: DCF77, MSF(Rugby), WWVB