#! perl -l
use strict;
use warnings;

my $s = 'uvXYZdabcXYZfg';

while ($s =~ /(\w\w\w)*?(XYZ)/g)
{
    print 'Found match ', $1, $2, ' at pos: ', pos $s;
}

print '-----';

while ($s =~ /(abc)*?(XYZ)/g)
{
    print 'Found match ', $1, $2, ' at pos: ', pos $s;
}

##</code><code>##

22:35 >perl 1476_SoPW.pl
Found match abcXYZ at pos: 12
-----
Use of uninitialized value $1 in print at 1476_SoPW.pl line 28.
Found match XYZ at pos: 5
Found match abcXYZ at pos: 12

22:35 >