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

my $dir = shift;   #dir = the argument given on the command line (./filechng.pl testdir)

find(\&change_ext_if_file, "$dir"); #loops through dir scooping up all it finds
                
    sub change_ext_if_file {   #called function

    my @files = @_;       #creates array

    foreach my $file (@files) {   ##loops through the array @files and places each file into scalar $file

     if ((-f $file) && ($file =~ /pdf$/)) {   #checks if file and if ends with pdf

            $file =~ s/pdf/doc/;    #replaces pdf with doc
    }
    }
    }