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journalctl

 
Query the systemd journal. More information: https://manned.org/journalctl.
 
  • Show all messages with priority level 3 (errors) from this [b]oot:
     
    journalctl -b --priority={{3}}
     
  • Show all messages from last [b]oot:
     
    journalctl -b -1
     
  • Delete journal logs which are older than 2 days:
     
    journalctl --vacuum-time={{2d}}
     
  • [f]ollow new messages (like tail -f for traditional syslog):
     
    journalctl -f
     
  • Show all messages by a specific [u]nit:
     
    journalctl -u {{unit}}
     
  • Filter messages within a time range (either timestamp or placeholders like "yesterday"):
     
    journalctl --since {{now|today|yesterday|tomorrow}} --until {{YYYY-MM-DD HH:MM:SS}}
     
  • Show all messages by a specific process:
     
    journalctl _PID={{pid}}
     
  • Show all messages by a specific executable:
     
    journalctl {{path/to/executable}}

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