Tut:Extending snmpd using shell scripts
From Net-SNMP Wiki
This tutorial is intended as a brief introduction to extending the snmpd agent using shell scripts.
Documentation
Shell scripts are configure in snmpd.conf. The man page for snmpd.conf has a section on EXTENDING AGENT FUNCTIONALITY which covers the exec, extend and pass methods.
There is also a FAQ on the differences between the various methods.
External examples
This article is mostly a place holder at the moment. Until it gets flushed out, here are some external examples we've found on the Internet: