journalctl: a log analyser from systemd
You can use journalctl
to analyse logs from systemd services by using a wide variety of filters. In order to access all logs, you need to be a root user or have superuser privileges.
These are some of the most useful parameters you can use with journalctl
:
-n
: shows the ten most recent logs. You can add a number after the parameter to specify a different amount.-u <unit>
: filter by a systemd unit.journalctl -u cronie
-p <priority>
: filters by priority. Shows logs with that priority or higher (which corresponds to a lower number): “emerg” (0), “alert” (1), “crit” (2), “err” (3), “warning” (4), “notice” (5), “info” (6), “debug” (7).journalctl -p err
-S <date>
: shows logs since<date>
. Date format:2021-01-01 12:00:00
(use double quotes, time part can be ommitted).journalctl -S "2021-10-01 12:00:00"
-U <date>
: shows logs until<date>
.-f
: shows most recent logs and updates the list in real time.
More parameters on the man page (man journalctl
).
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