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journalctl
Filtering by date/time
-b Show logs from the last boot.-b N Show logs from the n-th boot (use --list--boots to get boot index).--since "yyyy-mm-dd hh:MM:ss" Show logs since. Also the following keywords may be used instead of exact date/time: yesterday, today, tomorrow, or now. Alternatively, a numbered value may be used with or without - or + prefix or the keyword ago, e.g. 11 hour ago`.--until "yyyy-mm-dd hh:MM:ss" Show logs until. The same rules apply.
Other filtering
-u Show logs for unit, e.g. -u postgres.service. May be provided multiple times.-k or --dmesg Show kernel messages.-p N Show logs with specific priority (e.g. err, warning, info or their numeric value).
Controlling output
--no-pager-n or -n N Same as tail-f Follow logs as they appear.
Housekeeping
--disk-usage--vacuum-size=N Truncate logs up to size N (e.g. 1G).--vacuum-time=T Truncate logs up to T (e.g. 1years will delete entries that are older than a year).