title: How to determine Mac OS X version in shell script?
body: <p>I need to run make with one parameters set if it is running under Capitan and with other parameters in Sierra.
  In other words:
  I run in command line:</p>
  
  <blockquote>
    <p>sw_version
    ProductName: Mac OS X
    ProductVersion: 10.13.6</p>
  </blockquote>
  
  <p>How I can get the value of ProductVersion to the variable and check it
  if current  OS version &lt;10.13 then
  else</p>