title: What happens if a program is compiled while another instance is already running?
body: <p><code>$ g++ program.cpp</code></p>
  
  <p><code>$ ./a.out &amp;</code></p>
  
  <p>(program.cpp is modified.)</p>
  
  <p><code>$ g++ program.cpp</code></p>
  
  <p>How can the running process still produce accurate results if the executable is overwritten?</p>