Debugging system services

A checklist for debugging system and user services.

Systemd units

List failed system services:

systemctl --failed

List failed user services:

systemctl --user --failed

Inspect one unit and its recent logs:

systemctl status display-manager.service
systemctl --user status noctalia.service

Use status for a human-readable snapshot. It includes runtime state and recent journal lines, while show is better for scripts.¹

Journal logs

journalctl reads systemd’s structured journal and supports filters such as the current boot, system or user journal, unit names, and grep-style message matches.²

Read the current boot only:

journalctl -b --no-pager
journalctl --user -b --no-pager

Filter to a unit:

journalctl -b -u display-manager.service --no-pager
journalctl --user -b --user-unit noctalia.service --no-pager

Search messages for a word or regex:

journalctl --user -b -g 'noctalia|umbriel|pam' --no-pager

Crashes

coredumpctl debug opens the matching core in a debugger, and info PID prints metadata plus stack trace details when they are available.³

List and inspect coredumps:

coredumpctl list
coredumpctl info PID
coredumpctl debug PID

1. https://man7.org/linux/man-pages/man1/systemctl.1.html ↩

2. https://man7.org/linux/man-pages/man1/journalctl.1.html ↩

3. https://man7.org/linux/man-pages/man1/coredumpctl.1.html ↩