package module_1;
require Exporter;
@ISA = qw(Exporter);
@EXPORT_OK = qw($A);
our $A = 100;
1;

##</code><code>##

#/usr/bin/perl
# script_1.cgi
use strict;
use CGI ':standard';
use lib 'path/to/module';
use module_1 qw($A);

$A = 300;
print header,start_html,
h1("\$A = $A"),
a( {href=>"script_2.cgi"}, "script_2"),
end_html;

##</code><code>##

#/usr/bin/perl
# script_2.cgi
use strict;
use CGI ':standard';
use lib 'path/to/module';
use module_1 qw($A);

print header,start_html,
h1("\$A = $A"),
a( {href=>"script_1.cgi"} ,"script_1"),
end_html;