adjtime_config - Linux
Overview
adjtime_config is a command-line utility used to configure system timing parameters, such as frequency offset and maximum error adjustment. It provides fine-grained control over the Linux kernel’s timekeeping subsystem and is essential for high-precision timing applications.
Syntax
adjtime_config [OPTIONS ...]
Options/Flags
- -c, –current: Display the current values of all timing parameters.
- –freq=
: Set the frequency offset value (in parts-per-second). - –maxerror=
: Set the maximum error adjustment value (in microseconds). - –time=
: Set the current time (in seconds since the epoch). - -t, –timezone=
: Set the timezone (e.g., "Europe/Paris"). - -d, –debug: Enable debug logging.
- -h, –help: Display usage information.
Examples
Display current timing parameters:
$ adjtime_config -c
Set frequency offset and maximum error adjustment:
$ adjtime_config --freq=-10 --maxerror=50
Common Issues
Incorrect timezone format: Ensure that the timezone is specified in the correct format (e.g., "America/New_York").
Invalid frequency offset: The frequency offset value must be between -1000 and 1000 parts-per-second.
Security risks: Changing timing parameters can affect system stability. Use caution when adjusting these values.
Integration
Synchronize time with a remote server:
$ adjtime_config -t $(ntpd -q -gn)
Set frequency offset based on GPS data:
$ gpsd -nr | adjtime_config --freq=$(cat /dev/ttyACM0)
Related Commands
- ntpd: Network Time Protocol daemon
- gpsd: GPS daemon