title: 'require': no such file to load (LoadError): when running foreman
body: <p>I've got a foreman Procfile that runs a ruby script:</p>
  
  <p><code>concat: ruby bin/compile_scripts_for_dev_automatically.rb</code></p>
  
  <p>When I run the script, I get the following error:</p>
  
  <p><code>bin/compile_scripts_for_dev_automatically.rb:10:in 'require': no such file to load -- listen (LoadError)</code></p>
  
  <p>I'm requiring 'listen' with <code>require 'listen'</code></p>
  
  <p>I've checked that I only have one copy of ruby on my computer:</p>
  
  <pre><code>$ which -a ruby
  /usr/bin/ruby
  </code></pre>
  
  <p>And when I try to require <code>listen</code> in IRB, it works:</p>
  
  <pre><code>$ irb
  &gt;&gt; require 'listen'
  =&gt; true
  </code></pre>
  
  <p>What could be causing this problem?</p>