title: "cmake --build . [ -- -j<N> ]". What is this command and how do I get it to work? Installing ROOT
body: <p>I am trying to install ROOT v6.20.04 using CMake 3.17.0. This is my first time using CMake and I am also not familiar with installing software on macOS, so I am a bit lost. I am following the instructions from the INSTALL script. I've gotten to this point:</p>
  
  <pre><code>cmake --build . [ -- -j&lt;N&gt; ]
  </code></pre>
  
  <p>and I have no idea what it means. I naively just tried copying and pasting this into my terminal, though of course it gives back </p>
  
  <pre><code>N: No such file or directory
  </code></pre>
  
  <p>I am not sure what directory N should be in this case. Well, for any sort of path I put in for N (I'm in my build directory, so I tried the path to this) I always get the same error:</p>
  
  <pre><code>Unknown argument [
  Usage: cmake --build &lt;dir&gt; [options] [-- [native-options]]
  </code></pre>
  
  <p>Followed by a bunch of options. On top of "N", I am not sure what the "-j" option does and how to get it to work (the bracketing is also confusing and throwing an error. I'm not sure how to resolve this). I am looking at a list of CMake options and -j is not one of them.</p>
  
  <p>If I understood what this command was meant to be doing, I'd probably be able to figure this out, though I have no idea. Any help is much appreciated. </p>