title: Test whether command completed successfully in python script
body: <p>I have a python script that searches through a directory, and if any files were recently modified, it executes a command to run our modeling software along with another python script and generate a report. I have the report running currently, and I want to add on a section that if the report generation for some reason was aborted (the software didn't open, there was some error, etc), I want to know and send an email out stating that the run did not complete. Currently I have this below, but I realized that it returns zero since running the actual command worked, even if the report was not generated.</p>
  
  <blockquote>
  <pre><code>    ansa_call = "ansa_15.1.0 -nogui -exec       
      load_script:/path/SubstructureSummary.py -exec 'SubstructureSummary (\""+path+"\")'"
      print ansa_call
      ret = os.system(ansa_call)
      print ret
      if ret != 0:
              print 'sending email'
  </code></pre>
  </blockquote>
  
  <p>I have injected an error into the secondary script 'SubstructureSummary.py' so that it will be forced to err. How do I grab a return value that shows the incomplete run?</p>
  
  <p>Thank you!!</p>