title: What is the purpose of the : (colon) GNU Bash builtin?
body: <p>What is the purpose of a command that does nothing, being little more than a comment leader, but is actually a shell builtin in and of itself?</p>
  <p>It's slower than inserting a comment into your scripts by about 40% per call, which probably varies greatly depending on the size of the comment. The only possible reasons I can see for it are these:</p>
  <pre><code># poor man's delay function
  for ((x=0;x&lt;100000;++x)) ; do : ; done
  
  # inserting comments into string of commands
  command ; command ; : we need a comment in here for some reason ; command
  
  # an alias for `true'
  while : ; do command ; done
  </code></pre>
  <p>I guess what I'm really looking for is what historical application it might have had.</p>