The problem with -T is it's not very "intelligent". It will find a postscript graphics file, and call it text.

So you might want to do some intelligent filtering with a modules like MIME::Types.

use MIME::Types;
        my $mimetypes = MIME::Types->new;
        my MIME::Type $plaintext = $mimetypes->type('text/plain');
        print $plaintext->mediaType;   # text
        print $plaintext->subType;     # plain
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You could also do some extension testing depending on the type of files you have on your system.