Linux datetime
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Set timezone and clock on Linux
1. su to root
2. Find your timezone file under /usr/share/zoneinfo. For example:
/usr/share/zoneinfo/US/Pacific
3. OPTIONAL: backup the current timezone configuration:
cp /etc/localtime /etc/localtime.old
4. Create a symbolic link from the appropiate timezone to /etc/localtime.
ln -sf /usr/share/zoneinfo/US/Pacific /etc/localtime
or
ln -sf /usr/share/zoneinfo/America/Los_Angeles /etc/localtime
5. Use rdate or ntpdate to set the system time (ntpdate is better):
/usr/sbin/ntpdate time.nist.gov
or
/usr/bin/rdate time.nist.gov
6. Set the hardware clock to the system time:
/sbin/hwclock --systohc
Correct for clock drift
For where its not possible to run ntpd you may use adjtimex to correct for systematic drift.
aptitude install adjtimex
NIST
time.nist.gov
Time Sync radio broadcasts
radio broadcasts of UTC time. Most consumer "atomic" clocks use WWVB for radio sync. Time signals can also be received through GPS receivers.
- WWVB, Fort Collins, CO
- 60 kHz (binary carrier signal)
- WWV, Fort Collins, CO
- 2500, 5000, 10000 and 15000 kHz (broadcasts voice)
- WWVH, Kauai, HI
- 2500, 5000, 10000 and 15000 kHz (broadcasts voice)
- CHU, Ottawa, Ontario, Canada
- 3330, 7335 and 14670 kHz (broadcasts voice)
UTC
| UTC(GMT) | EDT | EST CDT | CST MDT | MST PDT | PST |
| 0000 | 8 PM | 7 PM | 6 PM | 5 PM | 4 PM |
| 0100 | 9 PM | 8 PM | 7 PM | 6 PM | 5 PM |
| 0200 | 10 PM | 9 PM | 8 PM | 7 PM | 6 PM |
| 0300 | 11 PM | 10 PM | 9 PM | 8 PM | 7 PM |
| 0400 | Midnight | 11 PM | 10 PM | 9 PM | 8 PM |
| 0500 | 1 AM | Midnight | 11 PM | 10 PM | 9 PM |
| 0600 | 2 AM | 1 AM | Midnight | 11 PM | 10 PM |
| 0700 | 3 AM | 2 AM | 1 AM | Midnight | 11 PM |
| 0800 | 4 AM | 3 AM | 2 AM | 1 AM | Midnight |
| 0900 | 5 AM | 4 AM | 3 AM | 2 AM | 1 AM |
| 1000 | 6 AM | 5 AM | 4 AM | 3 AM | 2 AM |
| 1100 | 7 AM | 6 AM | 5 AM | 4 AM | 3 AM |
| 1200 | 8 AM | 7 AM | 6 AM | 5 AM | 4 AM |
| 1300 | 9 AM | 8 AM | 7 AM | 6 AM | 5 AM |
| 1400 | 10 AM | 9 AM | 8 AM | 7 AM | 6 AM |
| 1500 | 11 AM | 10 AM | 9 AM | 8 AM | 7 AM |
| 1600 | Noon | 11 AM | 10 AM | 9 AM | 8 AM |
| 1700 | 1 PM | Noon | 11 AM | 10 AM | 9 AM |
| 1800 | 2 PM | 1 PM | Noon | 11 AM | 10 AM |
| 1900 | 3 PM | 2 PM | 1 PM | Noon | 11 AM |
| 2000 | 4 PM | 3 PM | 2 PM | 1 PM | Noon |
| 2100 | 5 PM | 4 PM | 3 PM | 2 PM | 1 PM |
| 2200 | 6 PM | 5 PM | 4 PM | 3 PM | 2 PM |
| 2300 | 7 PM | 6 PM | 5 PM | 4 PM | 3 PM |
