title: Install with Gem on macOS Catalina
body: <p>I was trying to install <a href="https://github.com/travis-ci/travis.rb" rel="noreferrer">Travis.rb</a> as documented by the team. However, the location that <code>gem</code> tried to install to is protected by the OS. So I got an error like this:</p>
  
  <pre><code>% gem install travis
  ERROR:  While executing gem ... (Gem::FilePermissionError)
      You don't have write permissions for the /Library/Ruby/Gems/2.6.0 directory.
  </code></pre>
  
  <p>I tried the following command but did not fully work - installation was okay, but I could not call <code>% travis</code>.</p>
  
  <pre><code>gem install travis --user-install
  </code></pre>
  
  <hr>
  
  <p>Configuration: I am using <code>gem</code> shipped with the OS:</p>
  
  <pre><code>% ruby -v  
  ruby 2.6.3p62 (2019-04-16 revision 67580) [universal.x86_64-darwin19]
  </code></pre>