Perl NetSNMP extension with multiple devices - perl

Question

I have got a machine (Debian based) with some temperature sensors attached to it, and i would like to query them over snmp, from one script. I can work with one sensor ok, but i am struggling when i plug another one in.
What I am trying to do is loop through each device, and give each one an id, then use this ID as part of the OID, then give it a value.
I've never worked with snmp before, and my perl is not great so any help would be much appreciated. Below is my code:
#!/usr/bin/perl
use NetSNMP::agent (':all');
use NetSNMP::ASN qw(ASN_OCTET_STR ASN_INTEGER);
$BASE_OID=".1.3.6.1.4.1.41050";
$dev_id=1;
$string_value;
$integer_value;
sub pimon_handler {
my ($handler, $registration_info, $request_info, $requests) = #_;
my $request;
my $oid_key;
for($request = $requests; $request; $request = $request->next()) {
$oid_key=$BASE_OID . '.' . $dev_id;
my $oid = $request->getOID();
if ($request_info->getMode() == MODE_GET) {
if ($oid == new NetSNMP::OID($oid_key . '.0')) {
$request->setValue(ASN_OCTET_STR, $string_value);
}
elsif ($oid == new NetSNMP::OID($oid_key . '.1')) {
$request->setValue(ASN_INTEGER, $integer_value);
}
} elsif ($request_info->getMode() == MODE_GETNEXT) {
if ($oid == new NetSNMP::OID($oid_key . '.0')) {
$request->setOID($oid_key . '.1');
$request->setValue(ASN_INTEGER, $integer_value);
}
elsif ($oid < new NetSNMP::OID($oid_key . '.0')) {
$request->setOID($oid_key . '.0');
$request->setValue(ASN_OCTET_STR, $string_value);
}
}
}
}
#location of where we are going to find the 1wire devices
#sensors = `cat /sys/bus/w1/devices/w1_bus_master1/w1_master_slaves`;
chomp(#sensors);
#loop through the sensors we find
foreach $line(#sensors) {
#work out the temp we have got. Need to change this for other sensor types
$output = `cat /sys/bus/w1/devices/$line/w1_slave`;
$output =~ /t=(?<temp>\d+)/;
$integer_value = sprintf "%.0f",$+{temp} / 1000;
$string_value = $line;
my $agent = new NetSNMP::agent();
$agent->register("Pimon$looptest", $BASE_OID . '.' . $dev_id,
\&pimon_handler);
print "Dev $dev_id temp $line temp is $integer_value\n";
$dev_id ++;
}

Answer 1

Are you getting any errors or output?
I suspect that your problem lies in and around your reading the data file by shelling-out to cat instead of opening the file and looping over the linewise contents.
Try dumping the value of #sensors. if it is a single entry array, with the only element containing your entire file, then simply switch #sensors to be scalar. then split $sensors into an array and loop over that.
my $sensors = `read something`
chomp $sensors;
my #sensors = split(/\n/, $sensors);
foreach $line (#sensors) {
...