file test1.pl:
#!/usr/bin/perl -w
use strict;
require 'test2.pl';
print $x;

file test2.pl:
#!/usr/bin/perl -w
use strict;
my $x = "this is it\n";
1;

>./test1.pl
Global symbol "$x" requires explicit package name at ./test1.pl line 4.
Execution of ./test1.pl aborted due to compilation errors.