i'am trying to realize a filtering script that when an interface goes down get an snmp value from the switch, using the IfIndex of the interface.

Here is my filtering script:

sub main() {
 
  transport = CreateSNMPTransport($node);    // Create SNMP transport for node
    
    ifIndex= %5;
     
    value = SNMPGetValue(transport, ".1.3.6.1.4.1.9.2.2.1.1.28.".ifIndex);
 
 
 
  CUSTOM_MESSAGE = "Description: ".value;
 
 
 
  return true;
}

The IfIndex of the interface is rapresented by the %5 special variable, because the filtering script is relative to "SYS_IF_DOWN" event which has as parameter:

"
  1) Interface object ID
  2) Interface name
  3) Interface IP address
  4) Interface netmask
  5) Interface index
"

But when the script is executed i get the following error code:

 Error in line 5: syntax error, unexpected T_INT32, expecting '('.

I have tryed to cast the value -> ifIndex = string(%5);

or

I have tryed to use a switch case to convert the value:

switch(%5):
  case "10134": etc

but nothing works

Can you help me?

Tnx