Initializing SNMP library.
Initializing RRDTOOL pipe.
sh line 1 /usr/local/rrdtool is a directory.
Closed MySQL connection.
Closed RRDTOOL pipe.
Cleaned up SNMP.
You have new mail in /var/spool/mail/root.
/bin/sh line 1 netmrg command not found
? HOW TO ? ..................
The path to rrdtool needs to be a path the the binary, not just the directory that it's in. Ie, if the binary is run as /usr/local/rrdtool/bin/rrdtool, that's what should go into the netmrg.xml file.