title: Permission denied to run shell script by subprocess.call
body: <p>I wrote a shell script using python and it successfully run by command <code>bash download_R1.sh</code> on my terminal.</p>
  <p>I wanted to test if subprocess can do the same thing in python because I would like to integrate a pipeline in python script. Here is the subprocess part of my code:</p>
  <pre><code>downR1 = subprocess.call('./download_R1.sh')
  </code></pre>
  <p>It failed to run the script with following error message:</p>
  <pre><code>Error message:
  PermissionError: [Errno 13] Permission denied: './download_R1.sh'
  </code></pre>
  <p>Someone suggested using <code>chmod +x</code> to obtain authenitification of that script. But <code>bash down.sh</code> is working. I don't know which part goes wrong.</p>
  <p>Any advice?</p>