Here is a powerful little renamer, but be careful, it can do some unexpected renaming unless you are careful.

#!/usr/bin/perl
#usage: zrn 'oldext' 'newext' 'topdir' 
#include the the . for extensions, otherwise anystring will change in 
+the filenames 
#if you want to append .bak to files, use $ for 'oldext' ex: zrn $ .ba
+k . 
#the ext is always applied to the end of the filename 
#to strip extensions: zrn .bak '' . 
use strict;
use File::Find;

my ($in,$out,$path) = @ARGV;
my $timestamp = localtime();
$timestamp =~ s/ /|/g;
if (@ARGV <2){die "Usage zrn 'oldext' 'newext' 'top directory' -> '.' 
+is good 
                   examples: zrn .bak .old .  
                             zrn  \$  .bak  . 
                             zrn  .bak ''  .\n"};
finddepth (\&wanted,$path);

sub wanted {
my $old = $_;
return unless -f; #-d for dir ops or comment out for both 
$_ =~ s/$in$/$out/; #do ops here 
if ($_ eq $old){return};
if (-e $_) {$_ = $_.$timestamp; warn("timestamping $_ to avoid overwri
+ting existing file")};
rename $old, $_ or warn "Cannot rename $old to $_ in $File::Find::dir:
+ $!";
};
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