Use of uninitialized value XXX in concatenation (.) or string (perl snmp)

Written by Claudio Kuenzler - 0 comments

Published on June 26th 2014 - Listed in Perl Linux

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While I was working on a Perl script which uses Net::SNMP, I got the following error:

Need to query .1.3.6.1.4.1.7933.1.20.2.1.1.14.1.15
Odd number of elements in hash assignment at /usr/lib/perl5/vendor_perl/5.16.2/Net/SNMP.pm line 2278.
Use of uninitialized value $enclosure in concatenation (.) or string at ./myscriptpl line 288.

What I was doing in my perl script was this:

      print "Need to query $oid_base.2.1.1.14.1.$oidend\n"; # debug
      my @oidlist2 = ($oid_base.2.1.1.14.1.$oidend);
      my $response = $session->get_request(-varbindlist => \@oidlist2);
      my $enclosure = $$response{"$oid_base.2.1.1.14.1.$oidend"};

Now the issue is that I missed the fact that I can't just put multiple variables together like this. It works correctly in the "print" line, because there I have set everything as a string in double-quotes.
In the definition of oidlist2, I forgot to use the double-quotes - so the OID wasn't really a SNMP OID anymore, which caused the snmp request to fail.

Ti simply put the oidlist2 definition into double-quotes solved that issue:

      #print "Need to query $oid_base.2.1.1.14.1.$oidend\n"; # debug
      my @oidlist2 = ("$oid_base.2.1.1.14.1.$oidend");
      my $response = $session->get_request(-varbindlist => \@oidlist2);
      my $enclosure = $$response{"$oid_base.2.1.1.14.1.$oidend"};
      #print "This drive is in Enclosure: $enclosure\n"; # debug

On my research "perl snmp Use of uninitialized value in concatenation" I did not find a single website pointing me to the solution. So once I figured it out myself, I thought I'd share that.

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