Difference between revisions of "Journalctl"

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{{lowercase}}
 
<code>journalctl</code> command allows to query the contents of the [[systemd]] journal/[[logs]].
 
<code>journalctl</code> command allows to query the contents of the [[systemd]] journal/[[logs]].
  
 
== Configuration ==
 
== Configuration ==
* <code>[[/etc/systemd/]][[journald.conf]]</code>
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* <code>[[/etc/systemd/journald.conf]]</code>
  
 
== Basic Commands ==
 
== Basic Commands ==
 
* <code>journalctl</code><ref>https://www.freedesktop.org/software/systemd/man/journalctl.html</ref> or <code>journalctl --[[no-pager]]</code>
 
* <code>journalctl</code><ref>https://www.freedesktop.org/software/systemd/man/journalctl.html</ref> or <code>journalctl --[[no-pager]]</code>
* <code>journalctl -r</code> (reverse order)
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* <code>[[journalctl -r]]</code> (reverse order)
 
* <code>journalctl -k</code>: Show only [[kernel]] messages
 
* <code>journalctl -k</code>: Show only [[kernel]] messages
* <code>journalctl -f</code> (follow)
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* <code>[[journalctl -f]]</code> (follow)
 
* <code>[[journalctl -u]] [[service-name]].service</code>
 
* <code>[[journalctl -u]] [[service-name]].service</code>
 
:: <code>-u unit_name</code>
 
:: <code>-u unit_name</code>
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::: <code>journalctl -u [[sshd|ssh]]</code> (See also [[sshd logs]])
 
::: <code>journalctl -u [[sshd|ssh]]</code> (See also [[sshd logs]])
 
::: <code>[[journalctl -u docker]]</code>
 
::: <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>
  
 
* <code>[[journalctl --verify]]</code>
 
* <code>[[journalctl --verify]]</code>
  
Disk Usage/Logging:  
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[[journalctl -xn --nopager]]
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 +
[[Disk Usage]]/Logging:  
 
* <code>[[journalctl --disk-usage]]</code>
 
* <code>[[journalctl --disk-usage]]</code>
 
* <code>journalctl --vacuum-time=2d</code>
 
* <code>journalctl --vacuum-time=2d</code>
* <code>journalctl --vacuum-size=200M</code><ref>https://askubuntu.com/a/1012913</ref>
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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
**--vacuum-time=TIME    Remove journal files older than specified time
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**[[--vacuum-time]]=TIME    Remove journal files older than specified time
* <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]]
 
:<code>-b </code> show message from current [[boot]]. if [ID] is provided will show messages from that specific [[boot]].
 
:<code>-b </code> show message from current [[boot]]. if [ID] is provided will show messages from that specific [[boot]].
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 +
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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>
  
 
== Activities ==
 
== Activities ==
* Review [[Libvirt error messages in journald]]
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* Review [[journalctl logs]]
* Review [[No space left on device]] messages
 
  
 
==See also==
 
==See also==
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* {{journalctl}}
 
* {{journalctl}}
 
* {{systemd}}
 
* {{systemd}}
* <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>
 
 
* [[launchd]] init and operating system service management daemon for [[MacOS]]
 
* [[launchd]] init and operating system service management daemon for [[MacOS]]
 
* {{logging}}
 
* {{logging}}
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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

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