note Riales <p>Does your code compile? O.o</p> <p>Anyways, I think you might be overcomplicating things. This seems to do what you want:</p> <code> my @stu = ( '103_dsu 1 35 nbu103', '104_dsu 1 35 nbu104', '204_tape 1 1 ACS1', '101_dsu 1 35 nbu101', ); my @dp = ( 'nbu103 Disk 6 -1', 'nbu104 Disk 6 -1', 'nbu101 Disk 6 -1', ); foreach my $stu (@stu) { my (undef, undef, undef, $possible) = split ' ', $stu; my ($matched_dp) = grep { my ($dp) = split ' ', $_; $dp eq $possible } @dp; $stu = $matched_dp if $matched_dp; } use Data::Dumper; print Dumper(@stu); </code> 963136 963136