my $working_dir = $ARGV[0];     # starting directory
my $extension   = $ARGV[1];     # extension to save

dedup($working_dir);
exit 0;

sub dedup {
    my $path = shift;
    my @files = glob("$path/*");
    print "Checking [$path] ...\n";

    foreach (@files) {
        dedup("$_") if (-d $_ && -x $_);        # recurse into subdirectories
        my ($base, $ext) = m/(.*)\.([^\.]+)$/;

        my @matches = glob("$base*");
        print "\tremoving: $_\n" if scalar @matches > 1 && $ext ne $extension;
#       unlink $_              if scalar @matches > 1 && $ext ne $extension;
    }
}

##</code><code>##

my @data;
while (<>) {
   my @fields = split ' ';
   my $col = $. - 1;
   for my $row (0..$#fields) {
      $data[$row][$col] = $fields[$row];
   }
}
foreach my $row (@data) {
        foreach (0 .. $#$row) {
                print $$row[$_];
        }
        print "\n";
}

##</code><code>##

use POSIX ":sys_wait_h";

my %kids = ();

# Signal Handler for SIGCHLD
sub sigchld_handler{
    while (($pid = waitpid(-1, &WNOHANG)) > 0) {
        delete $kids{$pid};
    }
    $SIG{CHLD} = \&sigchld_handler;
}
$SIG{CHLD} = \&sigchld_handler;

# You can repeat this for as many secondary
# processes as you need to merge the old indexes
for (1..3) {
        if (my $pid = fork) {
            # Parent Process keep track of forked children
            $kids{$pid} = 1;
        }
        else {
            # Child process
            # ... do merging of old indexes here
            sleep(3);
            exit 0;   # MUST EXIT HERE
        }
}

while (keys %kids > 0) {
     sleep(1);  # wait for all children to finish
}
exit 0;

##</code><code>##

# Straight forward way (sort keys slows down the larger the list)
my %hash = map { $_ => 1 } @items;
my @uniq = sort keys %hash;

# Using List::MoreUtils::uniq()
use List::MoreUtils qw(uniq);
my @uniq = uniq(@items);

# This is the method under the hood in List::MoreUtils::uniq
my %h;
my @uniq = map { $h{$_}++ == 0 ? $_ : () } @items;

##</code><code>##

# AC_CHECK_PM
#----------------------------------------------------------
AC_DEFUN([AC_CHECK_PM],[
AC_MSG_CHECKING([for module $1])
if `perl -M$1 -e '' >/dev/null 2>&1` ; then
        AC_MSG_RESULT([yes])
else
        AC_MSG_RESULT([no])
        AC_MSG_ERROR([missing perl module $1, not in @INC])
fi;dnl
])