systemd-delta

The command systemd-delta is used in Linux systems to compare and display differences between the distribution-provided systemd unit files and any local modifications made by the system administrator. Here’s a detailed overview of systemd-delta and its usage:

Purpose of systemd-delta

1. Configuration Management:

   • systemd-delta helps administrators manage configuration changes by showing differences between the original unit files provided by the distribution and any local modifications made.

2. Troubleshooting:

   • It aids in troubleshooting systemd-related issues by highlighting changes that could affect service behavior, startup sequences, dependencies, or other critical configurations.

Usage

• Listing Differences:

  • Running systemd-delta without arguments lists all systemd unit files where local modifications exist compared to the distribution-provided versions.

  systemd-delta

• Viewing Specific Unit Changes:

  • To view differences for a specific unit file (e.g., sshd.service), specify the unit name after systemd-delta.

  systemd-delta sshd.service

Example Output

When you run systemd-delta, it typically displays output similar to the following:

[EXTENDED] 0 overridden configuration files found.
[EXTENDED] No override file found for unit 'systemd-resolved.service'.
[EXTENDED] No drop-in files found for 'systemd-resolved.service'.
[EXTENDED] No override file found for unit 'sshd.service'.
1 overridden configuration files found.
Use 'systemctl cat <unit>' to see them.

Interpretation

• No Overrides: Indicates units where no local modifications (override) or customizations (drop-in files) have been made compared to the distribution-provided files.

• Overrides Found: Indicates units where local modifications (override) or customizations (drop-in files) exist, potentially altering the default behavior defined by the distribution.

Benefits

• Configuration Transparency: Provides clarity on which systemd unit files have been customized locally, aiding in system administration and maintenance.

• Consistency: Helps maintain consistency across systems by highlighting deviations from distribution-provided defaults.

Conclusion

systemd-delta is a valuable tool for system administrators managing systemd-based Linux systems. By showing differences in unit file configurations, it promotes clarity, transparency, and effective management of system services and configurations. Using systemd-delta allows administrators to identify, review, and manage local modifications efficiently, ensuring system stability and adherence to operational requirements.