title: How to check if currently running shell is BusyBox
body: <p>I tried different variants</p>
  
  <pre><code>echo $0
  echo $shell
  echo $SHELL
  ps -p $$
  </code></pre>
  
  <p>but none of them can give a distinctive output. I can do something like this but it's ugly and hackish:</p>
  
  <pre><code>if ls --help 2&gt;&amp;1 | grep BusyBox; then
      echo "it is BusyBox"
  else
      echo "it is NOT BusyBox"
  fi
  </code></pre>