adjtimex - Linux

Overview

adjtimex is a Linux command used to adjust the system’s clock, providing fine-grained control over various time parameters. It enables precise clock synchronization and correction, especially in critical applications where time accuracy is crucial.

Syntax

adjtimex [-f [file]] [-s [-i]] [-S [-i]] [-t [-i] [freq]] [-o [-i] [ofs]] [-m [-i] [max]] [-c] [-n] [-d] [-D] [-R] [-C] [modes]

Options/Flags

  • -f [file]: Read modes from the specified file. Default: /etc/adjtime
  • -s [-i]: Set the leap second mode (0: off, 1: auto, 2: manual). Default: 1
  • -S [-i]: Set the synchronization mode (0: false, 1: true). Default: 0
  • -t [-i] [freq]: Set the frequency adjustment (in parts per million). Default: 0
  • -o [-i] [ofs]: Set the time offset (in microseconds). Default: 0
  • -m [-i] [max]: Set the maximum allowed adjustment (in microseconds). Default: 500000
  • -c: Calibrate the clock.
  • -n: Disable frequency adjustment.
  • -d: Disable time offset adjustment.
  • -D: Disable maximum adjustment check.
  • -R: Reset all parameters to default values.
  • -C: Clear the calibration data.
  • modes: Specify a combination of the following modes:
    • i: Interrogate mode (display current settings)
    • e: Enhanced mode (extended precision)
    • p: Phase-locked loop mode
    • a: Automatic frequency adjustment mode

Examples

Display Current Time Settings:

adjtimex -i

Adjust Frequency manually by +10 PPM:

adjtimex -t 10

Disable Frequency Adjustment:

adjtimex -n

Calibrate Clock:

adjtimex -c

Common Issues

  • Clock Drift: If the clock is drifting significantly, check for hardware issues or consult a system administrator.
  • Time Offset Too Large: If the time offset is too large, consider investigating network synchronization issues or adjusting the max parameter.
  • Permission Denied: Ensure that you have root privileges or are authorized to execute adjtimex.

Integration

Network Time Synchronization: adjtimex can be used in conjunction with ntpd or other network time synchronization tools to maintain accurate system time.

Precise Clock Control: adjtimex allows for precise clock tuning in applications such as audio/video processing, scientific research, and financial trading.

Related Commands

  • ntpdate: Set the system time using a remote time server.
  • timedatectl: Display and configure system time and date settings.
  • crontab: Schedule tasks at specific times.