The rocket-fast system for log processing

Support module for external message modification modules

Module Name:    mmexternal

Available since: 8.3.0

Author:Rainer Gerhards <>


This module permits to integrate external message modification plugins into rsyslog.

For details on the interface specification, see rsyslog’s source in the ./plugins/external/

Action Parameters:

Note: parameter names are case-insensitive.

  • binary

    The name of the external message modification plugin to be called. This can be a full path name.

  • interface.input

    This can either be “msg”, “rawmsg” or “fulljson”. In case of “fulljson”, the message object is provided as a json object. Otherwise, the respective property is provided. This setting must match the external plugin’s expectations. Check the external plugin documentation for what needs to be used.

  • output

    This is a debug aid. If set, this is a filename where the plugins output is logged. Note that the output is also being processed as usual by rsyslog. Setting this parameter thus gives insight into the internal processing that happens between plugin and rsyslog core.

  • forcesingleinstance

    This is an expert parameter, just like the equivalent omprog parameter. See the message modification plugin’s documentation if it is needed.

Caveats/Known Bugs:

  • None.


The following config file snippet is used to write execute an external message modification module “”. Note that the path to the module is specified here. This is necessary if the module is not in the default search path.

module (load="mmexternal") # needs to be done only once inside the config

action(type="mmexternal" binary="/path/to/")

See also

If you would like to contribute to these docs, but are unsure where to start, please see the rsyslog-doc project README for an overview of the process. If you would like to contribute to the main source project, please review the contribution guidelines listed in the rsyslog project README.

If you have a question about these docs or Rsyslog in general, please see the following resources:

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