title: how to concatenate lines into one string
body: <p>I have a function in bash that outputs a bunch of lines to stdout. I want to combine them into a single line with some delimiter between them.</p>
  
  <p>Before: </p>
  
  <pre><code>one 
  two 
  three 
  </code></pre>
  
  <p>After: </p>
  
  <pre><code>one:two:three   
  </code></pre>
  
  <p>What is an easy way to do this?    </p>