title: Add column from one file to another based on multiple matches while retaining unmatched
body: <p>So I am <em>really</em> new to this kind of stuff (seriously, sorry in advance) but I figured I would post this question since it is taking me some time to solve it and I'm sure it's a lot more difficult than I am imagining.</p>
  
  <p>I have the file small.csv:</p>
  
  <pre><code>id,name,x,y,id2
  1,john,2,6,13
  2,bob,3,4,15
  3,jane,5,6,17
  4,cindy,1,4,18
  </code></pre>
  
  <p>and another file big.csv:</p>
  
  <pre><code>id3,id4,name,x,y
  100,{},john,2,6
  101,{},bob,3,4
  102,{},jane,5,6
  103,{},cindy,1,4
  104,{},alice,7,8
  105,{},jane,0,3
  106,{},cindy,1,7
  </code></pre>
  
  <p>The problem with this is I am attempting to put <code>id2</code> of the small.csv into the <code>id4</code> column of the big.csv only if the <code>name</code> AND <code>x</code> AND <code>y</code> match. I have tried using different <code>awk</code> and <code>join</code> commands in Git Bash but am coming up short. Again I am sorry for the newbie perspective on all of this but any help would be awesome. Thank you in advance.</p>
  
  <p>EDIT: Sorry, this is what the final desired output should look like:</p>
  
  <pre><code>id3,id4,name,x,y
  100,{13},john,2,6
  101,{15},bob,3,4
  102,{17},jane,5,6
  103,{18},cindy,1,4
  104,{},alice,7,8
  105,{},jane,0,3
  106,{},cindy,1,7
  </code></pre>
  
  <p>And one of the latest trials I did was the following:</p>
  
  <pre><code>$ join -j 1 -o 1.5,2.1,2.2,2.3,2.4,2.5 &lt;(sort -k2 small.csv) &lt;(sort -k2 big.csv)
  </code></pre>
  
  <p>But I received this error:</p>
  
  <pre><code>join: /dev/fd/63: No such file or directory
  </code></pre>