#!/usr/local/bin/perl

use strict;
use warnings;
use File::Find;


my @argv;
my $dir = $ARGV[0];

find(\&dirRecurs, $dir);

sub dirRecurs{


        if (-f)
        {
                (my $txt = $_) =~ s/pl$/txt/;
                rename($_, $txt);
        }
        if (-d)
        {
                 (my $txt = $_) =~ s/pl$/txt/;
                rename($_, $txt);
        }
}