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org.freedesktop.LogControl1 - D-Bus interface to query and set logging configuration


org.freedesktop.LogControl1 is a generic interface that is intended to be used by any daemon which allows the log level and target to be set over D-Bus. It is implemented by various daemons that are part of the systemd(1) suite.

It is assumed that those settings are global for the whole program, so a fixed object path is used. The interface should always be available under the path /org/freedesktop/LogControl1.


The following interface is exposed:

node /org/freedesktop/LogControl1 {
  interface org.freedesktop.LogControl1 {
      readwrite s LogLevel = '...';
      readwrite s LogTarget = '...';
      readonly s SyslogIdentifier = '...';
  interface org.freedesktop.DBus.Peer { ... };
  interface org.freedesktop.DBus.Introspectable { ... };
  interface org.freedesktop.DBus.Properties { ... };


LogLevel describes the syslog(3)-style log-level, and should be one of "emerg", "alert", "crit", "err", "warning", "notice", "info", "debug", in order of increasing verbosity.

LogTarget describes the log target (mechanism). It should be one of "console" (log to the console or standard output), "kmsg" (log to the kernel ring buffer), "journal" (log to the journal natively, see systemd-journald.service(8)), "syslog" (log using the syslog(3) call).

Those two properties are writable, so they may be set by sufficiently privileged users.

SyslogIdentifier is a read-only property that shows the "syslog identifier". It is a short string that identifies the program that is the source of log messages that is passed to the syslog(3) call.


journalctl option -p/--priority= may be used to filter log messages by log level, option -t/--identifier= may be used to by the syslog identifier, and filters like "_TRANSPORT=syslog", "_TRANSPORT=journal", and "_TRANSPORT=kernel" may be used to filter messages by the mechanism through which they reached systemd-journald.

systemctl log-level and systemctl log-target verbs may be used to query and set the LogLevel and LogTarget properties of the service manager. systemctl service-log-level and systemctl service-log-target may similarly be used for individual services. (Services must have the BusName= property set and must implement the interface described here. See systemd.service(5) for details about BusName=.)


systemd(1), journalctl(1), systemctl(1), systemd.service(5), syslog(3)
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