# Parser

The `parser` object, as its name suggests, describes message parsers. Message parsers have a standard parser name, which can be used by simply loading the parser module. Only when specific parameters need to be set the parser object is needed.

In that case, it is used to define a new parser name (aka “parser definition”) which configures this name to use the parser module with set parameters. This is important as the ruleset() object does not support to set parser parameters. Instead, if parameters are needed, a proper parser name must be defined using the parser() object. A parser name defined via the parser() object can be used wherever a parser name can occur.

Note that not all message parser modules are supported in the parser() object. The reason is that many do not have any user-selectable parameters and as such, there is no point in issuing a parser() object for them.

The parser object has different parameters:

- those that apply to all parser and are generally available for all of them. These are documented below.

- parser-specific parameters. These are specific to a certain parser module. They are documented by the parser module in question.

## General Parser Parameters

Note: parameter names are case-insensitive.

name <name-string>

  Mandatory

  This names the parser. Names starting with “rsyslog.” are reserved for rsyslog use and must not be used. It is suggested to replace “rsyslog.” with “custom.” and keep the rest of the name descriptive. However, this is not enforced and just good practice.

type <type-string>

  Mandatory

  The `<type-string>` is a string identifying the parser module as given it each module’s documentation. Do not mistake the parser module name with its default parser name. For example, the Cisco IOS message parser module parser module name is “pmciscoios”, whereas it’s default parser name is “rsyslog.pmciscoios”.

## Samples

The following example creates a custom parser definition and uses it within a ruleset:

    module(load="pmciscoios")
    parser(name="custom.pmciscoios.with_origin" type="pmciscoios")

    ruleset(name="myRuleset" parser="custom.pmciscoios.with_origin") {
       ... do something here ...
    }

The following example uses multiple parsers within a ruleset without a parser object (the order is important):

    module(load="pmaixforwardedfrom")
    module(load="pmlastmsg")

    ruleset(name="myRuleset" parser=["rsyslog.lastline","rsyslog.aixforwardedfrom","rsyslog.rfc5424","rsyslog.rfc3164"]) {
       ... do something here ...
    }

A more elaborate example can also be found in the Cisco IOS message parser module documentation.

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