Inspired by fingers' recent post, I decided it was time to tinker with Net::SNMP.   Snippet below shows my initial efforts.

The commented-out version at the bottom works fine, but is chock-full of evil copy+paste.   The section at the top is an attempt to use a tied hash to eliminate redundant code, but results in 

Use of uninitialized value at netsnmpTinker.pl line 34
sysDescr for host 'localhost' is
Use of unitialized value at netsnmpTinker.pl line 34.
sysUpTime for host 'localhost' is
Use of unitialized value at netsnmpTinker.pl line 34.
ifNumber for host 'localhost' is 
Use of unitialized value at netsnmpTinker.pl line 34.
ifTable for host 'localhost' is

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Near as I can tell, is choking on $snmp{response}->{$mib{key}},   What might I be doing wrong here?
    cheers,
    Don
    striving toward Perl Adept
    (it's pronounced "why-bick") 

#! /usr/bin/perl -w

# netsnmpTinker.pl
# ybiC   2001-05-18
# derived from Net::SNMP example1.pl

use strict;
use Net::SNMP;
use Tie::IxHash;

my %snmp;

($snmp{session}, $snmp{error}) = Net::SNMP->session(
    -hostname  => shift || 'localhost',
    -community => shift || 'public',
    -port      => shift || 161 
    );
print "\n";
unless (defined($snmp{session})) {
    printf("ERROR: %s.\n", $snmp{error});
    exit 1;
    }

# =cut

tie my %mib, "Tie::IxHash";
%mib = (
    sysDescr  => '1.3.6.1.2.1.1.1.0',
    sysUpTime => '1.3.6.1.2.1.1.3.0',
    ifNumber  => '1.3.6.1.2.1.2.1.0',
    ifTable   => '1.3.6.1.2.1.2.2.0',
    );
foreach my $key (keys %mib) {
    if (defined($snmp{response} = $snmp{session}->get_request($mib{key
+}))) {
        printf("$key for host '%s' is %s\n", 
            $snmp{session} ->hostname(), 
            $snmp{response}->{$mib{key}},
            );
        }
    else { printf("ERROR: %s.\n", $snmp{session}->error()) }
    }
$snmp{session}->close();
print "\n";
exit 0;

=cut

my $sysDescr  = '1.3.6.1.2.1.1.1.0';
my $sysUpTime = '1.3.6.1.2.1.1.3.0';
my $ifNumber  = '1.3.6.1.2.1.2.1.0';
my $ifTable   = '1.3.6.1.2.1.2.2.0';
if (defined($snmp{response} = $snmp{session}->get_request($sysDescr)))
+ {
    printf("sysDescr for host '%s' is %s\n", 
        $snmp{session}->hostname(), 
        $snmp{response}->{$sysDescr}
        );
    }
else { printf("ERROR: %s.\n", $snmp{session}->error()) }

if (defined($snmp{response} = $snmp{session}->get_request($sysUpTime))
+) {
    printf("sysUpTime for host '%s' is %s\n", 
        $snmp{session}->hostname(), 
        $snmp{response}->{$sysUpTime}
        );
    }
else { printf("ERROR: %s.\n", $snmp{session}->error()) }

if (defined($snmp{response} = $snmp{session}->get_request($ifNumber)))
+ {
    printf("ifNumber for host '%s' is %s\n", 
        $snmp{session}->hostname(), 
        $snmp{response}->{$ifNumber}
        );
    }
else { printf("ERROR: %s.\n", $snmp{session}->error()); }

if (defined($snmp{response} = $snmp{session}->get_request($ifTable))) 
+{
    printf("ifTable for host '%s' is %s\n", 
        $snmp{session}->hostname(), 
        $snmp{response}->{$ifTable}
        );
    }
else { printf("ERROR: %s.\n", $snmp{session}->error()); }

print "\n";
$snmp{session}->close();

exit 0;

=cut

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In reply to uninitialized value with Tie::IxHash and Net::SNMP by ybiC

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