clockdiff - Linux
Overview
clockdiff measures the performance characteristics of the system clock by calculating its drift per second from an external reference source, typically a GPS receiver. This information is valuable for applications requiring precise timing, such as financial trading, scientific research, and network time synchronization.
Syntax
clockdiff [options] <ntp server> <duration>
Options/Flags
- -h, –help: Display help information and exit.
- -V, –version: Display version information and exit.
- -d, –debug: Enable debug logging.
- -f, –frequency: Calculate the clock frequency in Hz.
- -s, –start: Start measuring at a specific time in seconds past epoch.
- -p, –pps: Use the PPS signal as the reference source.
- -c, –counts: Print the number of reference counts used for drift calculation.
Examples
Measure clock drift for 10 seconds using an NTP server:
clockdiff ntp.example.com 10
Display clock frequency in Hz:
clockdiff -f ntp.example.com 300
Start measuring after 10 seconds past epoch:
clockdiff -s 10 ntp.example.com 10
Common Issues
- NTP server unreachable: Ensure the NTP server is accessible and responds to requests.
- PPS signal not available: Not all systems have a PPS signal. Use the -s option to avoid this dependency.
- Drift calculation is inaccurate: Increase the duration or use a more reliable reference source.
Integration
Use with crontab: Automate periodic clockdrift measurements by adding commands to crontab, such as:
0 0 * * * clockdiff -s 10 ntp.example.com 300
Combine with other tools: Use clockdiff to provide accurate timing information for other applications, such as htop:
htop --check-frequency $(clockdiff -f ntp.example.com 60) -d
Related Commands
- ntpdate: Synchronize the system clock with an NTP server.
- hwclock: Manage the hardware clock.
- timedatectl: Display and control system time settings.