title: why does "npm run build" produce error "react-scripts Permission denied"?
body: <p>I'm on Ubuntu 18.04, logged in as root.  The group:owner of /root/.npm is root:root, recursively, and all permissions are 777, recursively.  If I cd to the React folder:</p>
  
  <pre><code>cd /var/lib/jenkins/workspace/MedAverter/medaverter-front
  </code></pre>
  
  <p>And set all permissions of that folder to 777, recursively and then run</p>
  
  <pre><code>npm run build
  </code></pre>
  
  <p>I get error:</p>
  
  <blockquote>
    <p>[[1;34mINFO[m] Running 'npm run build' in
    /var/lib/jenkins/workspace/MedAverter/medaverter-front
    [[1;34mINFO[m]  [[1;34mINFO[m] > medaverter-front@0.1.0 build
    /var/lib/jenkins/workspace/MedAverter/medaverter-front
    [[1;34mINFO[m] > react-scripts build [[1;34mINFO[m] 
    [[1;31mERROR[m] sh: 1: react-scripts: Permission denied
    [[1;31mERROR[m] npm ERR! code ELIFECYCLE [[1;31mERROR[m] npm ERR!
    errno 126 [[1;31mERROR[m] npm ERR! medaverter-front@0.1.0 build:
    <code>react-scripts build</code> [[1;31mERROR[m] npm ERR! Exit status 126
    [[1;31mERROR[m] npm ERR!  [[1;31mERROR[m] npm ERR! Failed at the
    medaverter-front@0.1.0 build script.</p>
  </blockquote>
  
  <p>I've been googling for a solution for hours with no luck.  It builds fine under Windows 10.
  Suggestions?</p>