title: Path, /usr/bin/ and /usr/local/bin/
body: <p>I installed <em>watchr</em> on OS X (10.8.3) using <code>gem install watchr</code>. And it's installed in <em>/usr/bin/watchr</em></p>
  
  <pre><code>$ which watchr
  /usr/bin/watchr
  </code></pre>
  
  <p>However, when I tried to call it <code>$ watchr -v</code>, the system couldn't find it.</p>
  
  <pre><code>$ watchr -v
  -bash: /usr/local/bin/watchr: No such file or directory
  </code></pre>
  
  <p>I think this is related to how the path is set up on my machine. My questions:</p>
  
  <ol>
  <li>What is the right way to fix it?</li>
  <li>In general, what programs should go to <code>/usr/bin/</code> vs. <code>/usr/local/bin/</code>?</li>
  <li>When I do e.g. <code>$ /usr/bin/watchr -e 'watch(./hello.txt) ...'</code>, are we looking at the <em>hello.txt</em> in the current directory or in <em>/usr/bin/</em> i.e. the same directory as <em>watchr</em>?</li>
  </ol>