title: Can't modify /System/Library/Frameworks
body: <p>I'm trying to install GLEW, based on <a href="https://www.cs.uaf.edu/2010/fall/cs381/docs/macGLEW_install.html" rel="nofollow noreferrer">this link</a>. But, when I tried to modify <code>/System/Library/Frameworks/</code>, even with sudo, I'm met with permission denied.</p>
  
  <pre><code>Enrico@~/D/g/M/b/Release sudo mv GLEW.framework/ /System/Library/Frameworks/
  mv: rename GLEW.framework/ to /System/Library/Frameworks/GLEW.framework/: Operation not permitted
  </code></pre>
  
  <p>Here's what the permissions look like:</p>
  
  <pre><code>Enrico@/S/Library ls -l | grep Frameworks
  drwxr-xr-x  139 root  wheel   4726 Sep  4 12:12 Frameworks
  </code></pre>
  
  <p>Also, when I inspect the folder in Finder with "Get info", it says at the bottom, "You can only read". Even though I can unlock the golden lock on the bottom right.</p>
  
  <p>Just to be clear, this question is not about GLEW. It's more about why I can't modify that folder, even with root user enabled.</p>
  
  <p>I'm on macOS Sierra.</p>
  
  <p>Any help would be much appreciated.</p>