#!/usr/bin/perl
$dir = "./test";
opendir(DIR,$dir) || die "NO SUCH Directory: $dir\n$!";

foreach $zips (readdir DIR){
    $new_name = $zips;
    $new_name =~ s/\.log/\.txt/ig;
    rename "$dir/$zips","$dir/$new_name" || die("Can't rename $zips\n$!");
}
close(DIR);