Ok, here is where I am now. I've made some progress as I found a typo in the command definition for ./check_snmp. I had $USER$ as my variable as opposed to the correct $USER1$ variable needed.
Once that was changed, I was no longer getting a CRITICAL error. However, I am getting another error (progress ;p) which is now telling me: check_snmp: Invalid warning threshold: %s
Ok, so this tells me that it doesn't like the percentage output that it received and therefore cannot display anything other than error.
Here is how the command is defined in the config:
$USER1$/check_snmp -H $HOSTADDRESS$ -C $ARG1$ -o $ARG2$ -w $ARG3$ -c $ARG4$
Now, here is how it's defined to check that device:
OK. That sums up how it's configured. And, when I run this from the command line on Nagios, I get a return of OK. Here is the command and the output from the command line:
./check_snmp -H host_ip -C passwd -o 188.8.131.52.184.108.40.206.1.58.0 -w 50 -c 70
SNMP OK: 43
SO, this proves that it works from the command line. And you can see that it matches the configuration. You would think that the output on the web interface side would be the output from the command line (SNMP OK - 43). It's not. I get the error mentioned above. (check_snmp: Invalid warning threshold: %s)
So, I do this: ./check_snmp --help
I see that the -w switch is looking for a range. You can specify a bare integer such as 40,50 etc...this will be interpreted as the max value before a warning is sent to output. OR, you could issue a range separated by colon like this 10:50, meaning that if the value is outside of that range, warning will output.
I've tried both options from command line (bare integer as well as range) and get SNMP OK - # both ways. So, we know that works.
So, I changed the configuration to use these two types of -warning checks, still get the same thing from the web interface. (check_snmp: Invalid warning threshold: %s)
My question is, what is Nagios expecting in return from the ./check_snmp command? AND, why would it NOT report the SNMP OK - # output that it does from the command line?