#!/usr/bin/perl -w

use strict;
use File::Find;

my $dir = '.'; # or wherever

find(\&myrename, $dir);

sub myrename {
	my $file1 = $_;
	my $file2 = $_;
	if ($file2 =~ s/\.abc$/.edf/) {
		print "renamed  $file1, $file2\n" if rename $file1, $file2;
	}
}