How to configure drush command-specific archive-dump --tar-options in a site alias
It should be like this - Edit: I've just confirmed that the following works as expected with Drush 6.3:

$aliases['example.com'] = array(
  'uri' =&gt; 'example.com',
  'root' =&gt; '/var/www/example.com/public_html',
  'command-specific' =&gt; array (
    'archive-dump' =&gt; array (
      'tar-options' =&gt; '--exclude=directory1 --exclude=sites/all/modules --exclude=*.txt',
    ),
  ),
);


I did notice that %files didn't work (Warning: sprintf(): Too few arguments exec.inc:138).