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Show only error logs since the last boot with journalctl

Filter the systemd journal to error-priority messages from the current boot, with timestamps, unit names, and full message text.

LinuxsystemTerminalDiagnosticsLow risk
Run journalctl -p err -b --no-pager to list every error (priority 3) or worse message logged since the machine booted.

01Command

Command
$ journalctl -p err -b --no-pager

02What it does

The -p err option filters by syslog priority: 'err' means priority 3 and journalctl also includes higher-severity levels (crit, alert, emerg) because filters match the minimum. -b limits output to the current boot; use -b -1 for the previous boot or omit it to search all retained logs. Drop --no-pager to browse interactively, and add -u nginx.service to narrow results to one unit. Check how much disk the journal uses with journalctl --disk-usage.

03Risk

RiskLow risk
RequirementsOn many distros you must be in the 'systemd-journal', 'adm', or 'wheel' group (or use sudo) to see all system units' logs
!Warning: Reading the journal is safe, but never delete journal files manually — use journalctl --vacuum-size or --vacuum-time to reclaim space.

04Undo

✓No undo needed — this command does not change persistent state.

05Sources

  • journalctl(1) — Query the systemd journal
    Ubuntu manpages · vendor-doc · 2026-09-17
    Evidence: The manual documents '-p' / '--priority=' to filter by message priority (e.g. err) and '-b' / '--boot' to limit output to a specific boot.
  • systemd/Journal - ArchWiki
    Arch Linux Wiki · community · 2026-09-17
    Evidence: The ArchWiki journal page shows filtering journalctl output by priority level and by current boot with examples like journalctl -p err -b.

Last verified: 2026-09-17 · Category: System & Settings

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