title: mac which finds the wrong directory for gcc
body: <p>Way beyond my depth here. I have installed gcc using brew. It's located in <code>/usr/local/Cellar/gcc</code> and the directory there is called 9.1.0. But when I type <code>which gcc</code> in a terminal it returns <code>/usr/bin/gcc</code>. In /usr/bin there is a file called gcc created by root with group wheel (If I remember what the columns mean). It's not a symlink. It's some kind of binary file. </p>
  
  <p>When I type <code>gcc --version</code>, I get back</p>
  
  <pre><code>Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
  Apple LLVM version 10.0.1 (clang-1001.0.46.4)
  Target: x86_64-apple-darwin18.7.0
  Thread model: posix
  InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
  </code></pre>