Desk checking your code, I suspected I understood the error. So I modified your code to show what you are actually asking the rename to do, and it was as expected: You are trying to rename the file to the same name it already has:

use File::Find;
use File::Basename;
use File::Spec;
use strict;

find ({ 'wanted' => \&renamefile }, 'c:\\folder1\\folder2');

sub renamefile {
    my $file = $_;
    return unless (-f $file);
    my $dirname = dirname($file);
    my $file_name = basename($file);
    my $new_file_name = $file_name;
    $new_file_name =~ s/\\\\/./g;

    print "\$file = [$file]\n";

    my $resulting_filename = File::Spec->catfile($dirname,$new_file_na
+me);
    print "\$resulting_filename = [$resulting_filename]\n";

    rename($file,File::Spec->catfile($dirname,$new_file_name))or die;
}

C:\Steve\Dev\PerlMonks\P-2013-08-06@1508-Rename-Fail>perl renameFailDe
+bug.pl
$file = [abc.txt]
$resulting_filename = [abc.txt]
[download]

Bottom line: You are supplying the unqualified filename and asking it to change all the backslashes (which by definition there are none) to dots.

Since there are no backslashes in an unqualified filename, you get back the same name you supplied.

$File::Find::dir is the current directory name,
$_ is the current filename within that directory
$File::Find::name is the complete pathname to the file.

marinersk pointed out the problem with your approach. A correct solution might be stated (below) using the 3 variables that come with File::Find.

Also notice that perl can read forward slashes on a Windows machine - it's not necessary to have backslashes.

This will rename all the files in folder1 and any subdirectories under it. (You might want to print out the proposed name changes before doing the operation to see that all is well.

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

find(\&wanted, '/folder1');

sub wanted {
    if (-f) {
        (my $new = $File::Find::name) =~ s/\//./g;
        print "$File::Find::dir/$new\n";
        #rename $File::Find::name, "$File::Find::dir/$new"
        #    or warn "Can't rename $File::Find::name\n";
    }
}
[download]

Nevermind, it works :)

If so something like this might work, although I can't test it on windows at the moment:

#!/usr/bin/perl
use strict;
use warnings;
my $path = 'C:\folder1\folder2\';

my @newName = split (/\\/, $path);
shift(@newName);
my $rename = join(".", @newName);

opendir (my $directory, $path) or die $!;
while(readdir $directory) 
    {
       
        next if $_ =~ m/^\./;
        my $fileName = "$rename" . ".$_";
        rename $_, $fileName;
    }
[download]

Beware, \' is special in single quotes.
لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

Thank you choroba, well spotted. Reason #121 not to use windows!! That would make it 'C:\folder1\folder2\\'. Is that right?

EDIT:People who use perl on windows must be that bit sharper, having to account for file separators also escaping special characters in perl code.

It not specific

c:\folder1 has many files
a.txt
b.txt
c.txt
output
.folder1.a.txt
.folder2.b.txt
.folder3.c.txt

then c:\folder1\folder2 (in subdir)
abc.txt
cde.txt
cfe.txt
output
.folder1.folder2.abc.txt
.folder1.folder2.cde.txt
.folder1.folder2.cfe.txt
and so on....

I rarely work with windows, and can't check this on windows, so you would have to switch the file separators in this. Also, I'm not certain that it's entirely safe to modify the @pathList array from the subroutine during the for loop. In any case this works for me, changing all the filenames in folders from the original path downwards:

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

my $originalPath = '/Path/To/file/';
my @pathList = ("$originalPath");

redoName($originalPath);
for (@pathList)
    {
        redoName($_);
    }

sub redoName
    {
        my $path = $_[0];
        my @newName = split (/\//, $path);
        shift(@newName);
        my $newName = join(".", @newName);

        opendir (my $directory, $path) or die $!;
        while(readdir $directory) 
            {
                my $fullName = "$path" . "$_";
                unless (-d $fullName)
                    {
                        next if $_ =~ m/^\./;
                        my $fileName = "$path" . "$newName" . ".$_";;
                        rename $fullName, $fileName or die "couldn't r
+ename: $!\n";
                    }

                if (-d "$fullName")
                    {
                        next if $_ =~ m/^\./;
                        my $newPath = "$path" . "$_" . "\/";
                        push (@pathList, $newPath);
                    }
            }
    }
[download]