Ah, the joys of debugging global variables! Iron-clad employment insurance!! You'll be working on this until the end of time — or until the company goes under, not unlikely if they've got a lot of code like this.

Here's one approach, not necessarily the best: track down the package the hash lives in (assuming it's a package global):

c:\@Work\Perl\monks>perl -wMstrict -le
"no strict qw(refs vars);
 no warnings;
 ;;
 package Foo;
 %CONTACTS = ('hello' => 'sailor');
 ;;
 package Bar;
 $ZOT{'autovivified'} = 'bam';
 ;;
 package main;
 ;;
 my $rx_pkg = qr{ \A (?: [[:alpha:]] [[:alnum:]]* ::)+ \z }xms;
 ;;
 print qq{'$_'} for
   grep m{ $rx_pkg }xms,
   keys %main::
   ;
 print '';
 ;;
 print qq{'$_' has 'CONTACTS'} for
   grep exists ${$_}{CONTACTS},
   grep m{ $rx_pkg }xms,
   keys %main::
   ;
 print '';
 ;;
 print qq{'$_' has 'ZOT'} for
   grep exists ${$_}{ZOT},
   grep m{ $rx_pkg }xms,
   keys %main::
   ;
 print '';
 ;;
 print $Foo::CONTACTS{'hello'};
 print $Bar::ZOT{'autovivified'};
"
'version::'
'utf8::'
're::'
'CORE::'
'DynaLoader::'
'mro::'
'strict::'
'Win32CORE::'
'Bar::'
'Regexp::'
'UNIVERSAL::'
'Foo::'
'main::'
'Carp::'
'Win32::'
'PerlIO::'
'IO::'
'Exporter::'
'Internals::'
'warnings::'
'DB::'

'Foo::' has 'CONTACTS'

'Bar::' has 'ZOT'

sailor
bam
[download]

• This code only runs if some strictures are disabled (no strict qw(refs vars);) — and it doesn't hurt to disable warnings also — you may have to turn all these off locally;
• This shows the package the hash lives in, but how it got there is another story;
• The example code shows hash definition in Foo, autovivification in Bar. For your purposes, they amount to the same thing.

Updates:

1. Added
       no strict qw(refs vars);
       no warnings;
   statements to example code.
2. Check out Packages and Symbol Tables in perlmod.
3. Actually, on re-reading the docs, I think
       my $rx_pkg = qr{ \A (?: [[:alpha:]_] \w* ::)+ \z }xms;
   would be a better definition of the package name regex.

grep -r 'CONTACTS.*=' .
[download]

to find code that populates the hash.

  DB<1> w %CONTACTS
[download]

mdskrzypczyk,

When you use a hash:

     $Hash{"HashID"} = 0;
[download]

     my %Hash = ();    # or just 'my %Hash;'
[download]

Regards...Ed

How have you looked in your code? When you do grep -rn 'CONTACTS' * in the root directory of your code, every result is $CONTACTS{...}?

Upate: show complete command
The way forward always starts with a minimal test.

I've been looking for the declaration somewhere in the files and have not managed to find it anywhere

Perl doesn't require declarations.

Some piece of code puts data in %CONTACTS, some other piece of code uses it. This is kind of a bad programming style, but you run into it a lot in legacy code. You'll just have to look for anything that looks like it's storing data in there.

How are you searching? An eyeball search, or a grep search? You could be grepping for my %CONTACTS in code that uses our %CONTACTS, or my (%CONTACTS), or %Foo::CONTACTS = (...), or use vars qw/%CONTACTS/;. Lots of search terms that could apply.

Maybe this is code that uses tie to tie %CONTACTS to a database.

At the top level of your code's directory structure try:

...and see what you get. It could be nothing. But since nothing else has worked out yet, it doesn't hurt to try.

mdskrzypczyk,

Using <code> ... </code>, please show an example of how 'CONTACTS' is used.

It may help us help you.

Regards...Ed