title: How to concatenate a fixed string and a variable in Python
body: <p>I want to include a file name, 'main.txt', in the subject. For that I am passing a file name from the command line. But I get an error in doing so:</p>
  <pre><code>python sample.py main.txt # Running 'python' with an argument
  
  msg['Subject'] = &quot;Auto Hella Restart Report &quot;sys.argv[1]  # Line where I am using that passed argument
  </code></pre>
  <p>How can I fix this problem?</p>