Hello, your code is very confusing: especially the nested open part. You are opening for read every file in each subdirectory and while reading them (ie for every line!) you open a file in append mode and write the content of the line to it...

Meaningfull names for variables and a correct indentation (perltidy) help a lot reading code or maintain it after a while.

If your usage of File::Find::Rule is correct (you grab first level or nested dirs?) you can try something like:

# untested
foreach my $dir (@subdirs) {
        # if you have .. you have also .
        next if ($dir eq ".");
        next if ($dir eq "..");

        my @files = File::Find::Rule->file()->name('*.*')->in($dir);
        
        # compose a filename:
        # you probably need a path not just a name; you have not cd to
+ the inside directory
        # many module can hadle this for you, but you can deal with a 
+relative path too
        my $outputname = "./$dir/List.txt";
        
        # open ALWAYS a lexical FH using the 3 args form.. 
        open my $lexical_filehandle, '>', $outputname or die "Cannot w
+rite to $outputname";
        
        # print each filename to the listfile
        print $lexical_filehandle "$_\n" for @files;
        close $lexical_filehandle;
}#next dir will be processed
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L*

PS you can also play with:

  find . -type d -maxdepth 1 | perl -lne "system qq(ls $_ > ./$_/_list
+.txt)"
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