use warnings;
use strict;
use File::Find qw(find);
use File::Basename qw(basename);
use Carp qw(croak);

croak "Usage: perlscript.pl <drectory_name>" unless defined $ARGV[0];
my $directory_name = $ARGV[0];

find( \&work_n_save, $directory_name ); # transverse the directory for each file

sub work_n_save {
    return if $_ eq '.' or $_ eq '..';
    my $filename = $File::Find::name if !-d;   ## get file name if not directory
    $filename = basename($filename);           ## get the file base name
    $filename =~ s/\..+$//;                    ## remove the file extention
    open my $fh_new, '>', $filename . "_new.txt" or croak "can't open file: $!";
    open my $fh, '<', $_ or croak "can't open file: $!";
    while ( defined( my $line = <$fh> ) ) {
        chomp $line;
          ## do whatever you want
        print {$fh_new} $line, $/;
    }
}