remove common words from files

#!/usr:bin/perl
use strict;
use warnings;

my $target = $ARGV[0];
my $delim = '_';

my @filenames = `ls $target`;
my %common_words;
my $first=1;
for my $filename (@filenames)
{
        chomp($filename);                       # remove trailing newline if any
        #$filename =~s/\.[^.]+$//;              # remove extention, beware with doubles like ".tar.gz"
        my @words = split($delim, $filename);
        print "words : @words\n";
        if( $first )
        {
                print "first name : $filename\n";
                foreach (@words)
                {
                        $common_words{$_} = 1;
                }
                $first = 0;
        }
        else
        {
                print "non-first name : $filename\n";
                foreach my $word (keys %common_words)
                {
                        if (not grep(/$word/,@words))
                        {
                                delete $common_words{$word};
                        }
                }
        }
}
foreach my $filename (@filenames)
{
        foreach my $word (keys %common_words)
        {
                my $filename_new = $filename;
                $filename_new =~ s/$word$delim//g;
                $filename_new =~ s/$delim$word//g;
                system "mv $target$filename $target$filename_new";
                $filename = $filename_new;
        }
}