title: Opposite of Linux Split
body: <p>I have a huge file and I split the big file into several small chunks and divide and conquer. Now I have a folder contains a list of files like below:</p>
  
  <pre><code>output_aa #(the output file done: cat input_aa | python parse.py &gt; output_aa)
  output_ab
  output_ac
  output_ad
  ...
  </code></pre>
  
  <p>I am wondering is there a way to merge those files back together FOLLOWING THE INDEX ORDER:</p>
  
  <p>I know I could do it by using</p>
  
  <pre><code>cat * &gt; output.all 
  </code></pre>
  
  <p>but I am more curious another magical command already exist comes with split..</p>