title: Using sed to replace a pattern by symbol
body: <p>How do I replace a pattern by looking at sentence symbol by using sed?<br>
  Input</p>
  
  <pre><code>this-
  -this-
  </code></pre>
  
  <p>Results I want</p>
  
  <pre><code>start
  middle
  </code></pre>
  
  <p>My code</p>
  
  <pre><code>sed 's/[a-zA-Z]-/start/g'
  sed 's/-[a-zA-Z]-/middle/g'
  </code></pre>
  
  <p>Results I get</p>
  
  <pre><code>abastart
  </code></pre>
  
  <p>Am I doing something wrong?</p>