Question

我正在尝试实现用perl编写的slapd_ munin插件，我几乎无能为力。 The full plugin is available here。我得到的错误就是这个：

Use of uninitialized value in concatenation (.) or string at
/etc/munin/plugins/slapd_localhost line 232, <DATA> line 275.

第232行就是这个：

 my $searchdn = $ops{$action}->{'search'} . "," . $basedn;

我尝试通过输出所有变量/对象进行调试，如下所示：

use Data::Dumper;   # top of script
# [...]
print Dumper(%ops);
print "action = [$action]\n";
print "basedn = [$basedn]\n\n";
my $searchdn = $ops{$action}->{'search'} . "," . $basedn;

当我再次运行时，这是我获得的：

[...] # 15 other variables belonging to $ops
$VAR16 = {
           'info' => 'The graph shows the number of Waiters',
           'search' => 'cn=Waiters',
           'desc' => 'The current number of Waiters',
           'filter' => '(|(cn=Write)(cn=Read))',
           'title' => 'Number of Waiters',
           'label2' => {
                         'read' => 'Read',
                         'write' => 'Write'
                       },
           'vlabel' => 'Waiters'
         };
action = [localhost]
action = [cn=Monitor]

Use of uninitialized value in concatenation (.) or string at /etc/munin/plugins/slapd_localhost line 237, <DATA> line 275.

由于似乎设置了所有变量，我真的不明白我得到的错误信息

问：有人可以就如何调试此脚本提供建议吗？

Answer 1

您应该将引用转储到%ops，如

print Dumper \%ops;

这将使调试输出更清晰。为了说明，请考虑

的输出

#! /usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

my %h = (foo => { bar => 1 }, baz => { quux => 3 });

print "No reference:\n",
      Dumper(%h),
      "\n",
      "Reference:\n",
      Dumper(\%h);

请注意在后半段你如何更清楚地看到结构：

No reference:
$VAR1 = 'baz';
$VAR2 = {
          'quux' => 3
        };
$VAR3 = 'foo';
$VAR4 = {
          'bar' => 1
        };

Reference:
$VAR1 = {
          'baz' => {
                     'quux' => 3
                   },
          'foo' => {
                     'bar' => 1
                   }
        };

你削减了输出的关键位。 $VAR15的价值是多少？是"localhost"还是其他什么？

当您打印$searchdn时，它的价值是什么？

在连接（。）中使用未初始化的值或在slapd_ munin插件中使用字符串

1 个答案: