title: Merge two unsorted text files based on the first column of the first one and preserving the order
body: <p>On Linux, how can I merge two unsorted text files based on the first column of the first file and preserving the order (from the first file).</p>
  
  <p>The first one:</p>
  
  <pre><code>DAC
  CAD
  ADC
  BAC
  </code></pre>
  
  <p>The second one:</p>
  
  <pre><code>CAD:word
  DAC:dog
  BAC:house
  </code></pre>
  
  <p>Merged files:</p>
  
  <pre><code>DAC:dog
  CAD:word
  ADC
  BAC:house
  </code></pre>
  
  <p>As I said, the lines of the merged file must be in the same order of the first file.</p>
  
  <p>Thank you in advance.</p>