Difference between revisions of "Journalctl"

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Journalctl command allows to query the contents of the [[systemd]] journal/[[logs]].
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{{lowercase}}
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<code>journalctl</code> command allows to query the contents of the [[systemd]] journal/[[logs]].
  
 
== Configuration ==
 
== Configuration ==
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* <code>/etc/systemd/journald.conf</code>
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* <code>[[/etc/systemd/journald.conf]]</code>
  
 
== Basic Commands ==
 
== Basic Commands ==
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* <code>journalctl</code><ref>https://www.freedesktop.org/software/systemd/man/journalctl.html</ref> or <code>journalctl --no-pager</code>
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* <code>journalctl</code><ref>https://www.freedesktop.org/software/systemd/man/journalctl.html</ref> or <code>journalctl --[[no-pager]]</code>
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* <code>journalctl -r</code> (reverse order)
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* <code>[[journalctl -r]]</code> (reverse order)
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* journalctl -k : Show only [[kernel]] messages
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* <code>journalctl -k</code>: Show only [[kernel]] messages
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* <code>journalctl -f</code> (follow)
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* <code>[[journalctl -f]]</code> (follow)
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* <code>journalctl -u service-name.service</code>
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* <code>[[journalctl -u]] [[service-name]].service</code>
 
:: <code>-u unit_name</code>
 
:: <code>-u unit_name</code>
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::<code>journalctl -u [[kVM/libvirt|libvirtd]]</code>
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:: <code>journalctl -u service-name.service -f</code>
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* <code>journalctl --verify</code>
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:::<code>[[journalctl -u libvirtd]]</code>
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* Disk Usage/Logging: <code>[[/journalctl --disk-usage/]]</code>
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::: <code>journalctl -u [[sshd|ssh]]</code> (See also [[sshd logs]])
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* <code>journalctl --vacuum-size=200M</code><ref>https://askubuntu.com/a/1012913</ref>
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::: <code>[[journalctl -u docker]]</code>
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::: <code>[[journalctl -u prometheus]]</code>
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::: <code>journalctl -u UNIT_NAME -n 1 -o verbose</code>
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* <code>[[journalctl --verify]]</code>
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[[journalctl -xn --nopager]]
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[[Disk Usage]]/Logging:  
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* <code>[[journalctl --disk-usage]]</code>
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* <code>journalctl --vacuum-time=2d</code>
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* <code>[[journalctl --vacuum-size]]=200M</code><ref>https://askubuntu.com/a/1012913</ref>
 
**--vacuum-size=BYTES  Reduce disk usage below specified size
 
**--vacuum-size=BYTES  Reduce disk usage below specified size
 
**--vacuum-files=INT    Leave only the specified number of journal files
 
**--vacuum-files=INT    Leave only the specified number of journal files
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**--vacuum-time=TIME    Remove journal files older than specified time
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**[[--vacuum-time]]=TIME    Remove journal files older than specified time
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* <code>journalctl --list-boots</code>. See also: <code>last (command)</code>
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* <code>journalctl --list-boots</code>. See also: <code>[[last (command)]]</code>
 
* <code>journalctl -xb</code>
 
* <code>journalctl -xb</code>
 
:<code>-x --catalog</code> Includes explanations in log lines from [[message catalgog]]
 
:<code>-x --catalog</code> Includes explanations in log lines from [[message catalgog]]
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:<code>-b </code> show message from current boot. if [ID] is provided will show messages from that specific [[boot]].
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:<code>-b </code> show message from current [[boot]]. if [ID] is provided will show messages from that specific [[boot]].
 +
 
 +
 
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* <code>journalctl --since "2 days ago"</code>
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== Related terms ==
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* <code>[[docker run]] -d --[[log-driver]]=[[journald]] YOUR_CONTAINER</code>
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* [[rsyslogd]]
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* <code>journalctl --identifier=[[ignition]] --all</code>
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== Activities ==
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* Review [[journalctl logs]]
  
 
==See also==
 
==See also==
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* {{journald}}
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* {{journalctl}}
 
* {{systemd}}
 
* {{systemd}}
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* <code>/etc/[[inittab]]</code><ref>https://linux.die.net/man/5/inittab</ref> and <code>respawn</code> option<ref>https://superuser.com/questions/507576/how-to-automatically-restart-a-linux-background-process-if-it-fails</ref>
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* [[launchd]] init and operating system service management daemon for [[MacOS]]
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* <code>[[systemctl]]</code>
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* {{logging}}
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* [[launchd]] init and operating system service management daemon for [[MacOS]]  
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* {{du}}
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{{CC license}}  
 
{{CC license}}  
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[[Category:Linux]]
 
[[Category:Linux]]
 
[[Category:Systemd]]
 
[[Category:Systemd]]
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[[Category:journalctl]]

Latest revision as of 12:05, 28 September 2023

journalctl command allows to query the contents of the systemd journal/logs.

Configuration[edit]

Basic Commands[edit]

-u unit_name
journalctl -u service-name.service -f
journalctl -u libvirtd
journalctl -u ssh (See also sshd logs)
journalctl -u docker
journalctl -u prometheus
journalctl -u UNIT_NAME -n 1 -o verbose
journalctl -xn --nopager

Disk Usage/Logging:

-x --catalog Includes explanations in log lines from message catalgog
-b show message from current boot. if [ID] is provided will show messages from that specific boot.


  • journalctl --since "2 days ago"

Related terms[edit]

Activities[edit]

See also[edit]

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Source: https://en.wikiversity.org/wiki/Linux_Administration/System_Services/System_Logging/Journalctl

  1. ↑ https://www.freedesktop.org/software/systemd/man/journalctl.html
  2. ↑ https://askubuntu.com/a/1012913
  3. ↑ https://wiki.ubuntu.com/DebuggingSystemd
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