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Revision as of 08:36, 8 June 2009

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<CODE>'exec'</CODE> will fork off the specified command and return the exit status

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<CODE>'exec'</CODE> will run the specified command and return the exit status

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and/or the output.  Any arguments are passed directly to the command.

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and output.  Any arguments are passed directly to the command, with no special interpretation.

<CODE>'sh'</CODE> is similar, but invokes a shell to run the command line given.

<CODE>'sh'</CODE> is similar, but invokes a shell to run the command line given.

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None of these mechanisms require the command to have any

None of these mechanisms require the command to have any

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knowledge of the fact that they are being used in this manner.

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knowledge of SNMP, or the fact that they are being used in this manner.

But the output is returned in a fixed format, and it is up to

But the output is returned in a fixed format, and it is up to

the receiving application to interpret this appropriately.

the receiving application to interpret this appropriately.

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<CODE>'pass'</CODE> is a more general mechanism for implementing

<CODE>'pass'</CODE> is a more general mechanism for implementing

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arbitrary MIB objects. The specified command will be invoked for any request within the named MIB subtree, and should return the information

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arbitrary MIB objects. The specified command will be invoked for any request within

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the named MIB subtree, and passed details of the requested OID.  It

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should return the information

relevant to the requested OID.

relevant to the requested OID.

<CODE>'pass-persist'</CODE> is similar, but the command will continue running even after the initial request has been answered.

<CODE>'pass-persist'</CODE> is similar, but the command will continue running even after the initial request has been answered.

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These two mechanisms

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can be used to implement a particular MIB, following the correct MIB

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structure (as opposed to the fixed format of exec/sh/extend).

All of these mechanisms are described in the <CODE>'snmpd.conf(5)'</CODE>

All of these mechanisms are described in the <CODE>'snmpd.conf(5)'</CODE>

man page, in the section entitled ''Extending Agent Functionality''.

man page, in the section entitled ''Extending Agent Functionality''.

← Older revision		Revision as of 07:56, 6 August 2009
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	But the output is returned in a fixed format, and it is up to		But the output is returned in a fixed format, and it is up to
	the receiving application to interpret this appropriately.		the receiving application to interpret this appropriately.
		+
		+	Note that the "relocatable" form of the <CODE>'exec'</CODE> directive
		+	(<CODE>exec <I>OID</I> ....</CODE>) produces MIB output that is not strictly valid.
		+	For this reason, support for this has been deprecated in favour of
		+	<CODE>extend <I>OID</I> ... </CODE>, which produces well-formed MIB results
		+	(as well as providing fuller functionality).<BR>
		+	The most recent releases of the agent don't include support for
		+	"relocatable exec" by default. This needs to be explicitly included
		+	when the agent is first compiled, by including the module <CODE>ucd-snmp/extensible</CODE>
		+	instead of <CODE>agent/extend</CODE>.

Template:FAQ:Agent 07 - Revision history

Dts12: Expand on exec vs. extend