title: What is the meaning of {} \; in find -exec sed
body: <p>Given two examples of sed.</p>
  
  <pre><code>sed -i 's/ugly/beautiful/g' /home/bruno/old-friends/sue.txt
  </code></pre>
  
  <p>This is easy for me to understand.</p>
  
  <p>But this:</p>
  
  <pre><code>$ find /home/bruno/old-friends -type f -exec sed -i 's/ugly/beautiful/g' {} \;
  </code></pre>
  
  <p>Why is <code>{} \;</code> important in the second one? What the significance and meaning of this?
  I assume `;' is for -exec. But why should it be escaped and what does the braces mean? Can they be imagined to be similar to C function's scope?</p>