<p>The <a href="http://meta.stackexchange.com/questions/64068/is-it-possible-to-post-questions-across-a-couple-of-the-sites-because-its-debata/64073#64073">official answer</a> to <a href="http://meta.stackexchange.com/questions/64068/is-it-possible-to-post-questions-across-a-couple-of-the-sites-because-its-debata">Is it possible to post questions across a couple of the sites because it's debatable which site it fits best?</a> is:</p>

<blockquote>
  <p>Allowing cross-posting is a slippery slope.</p>
  
  <p>If you might have slightly better odds of getting an answer by posting it on two sites, well, by gum, why not maximize your odds by posting it on twenty sites!</p>
  
  <p>There are some questions which fall into grey areas between sites, and I think it's OK to ask and delete, then re-ask if you feel you have asked on the wrong site.</p>
  
  <p>But as a general rule, do not cross-post questions, please. Pick a site and go with it.</p>
</blockquote>

<p>If you regret your initial choice and want to change sites, I recommend <strong>flagging for migration</strong> rather than deleting and re-asking, in case someone has seen the question and is preparing an answer.</p>

<hr>

<p>Unix and Linux's FAQ explicitly says <strong>not to cross-post</strong>:</p>

<blockquote>
  <p>Cross-posting is strongly discouraged -- if you post on one site and then change your mind it can always be migrated to another. If you're not sure if your question is on-topic, ask on meta or just give it a try and the community will decide.</p>
</blockquote>

<p>So <strong>Do not post the same question on both Ask Ubuntu and Unix &amp; Linux</strong>. When a question is cross-posted to U&amp;L and other sites, what normally happens is that all but one instance of the question are deleted. You get a warning the first time, and doing it routinely would be considered abuse.</p>

<hr>

<p>By the way, althought the term “cross-post” is often used, there is technically no cross-posting facility on Stack Exchange. A given question exists on a single site; if you post questions with identical contents, that's a multi-post.</p>