title: See changes to a specific file using git
body: <p>I know that I can use the <code>git diff</code> command to check the changes, but, as far as I understood, it is directory based. This means it gives all the changes of all files on the current directory.</p>
  
  <p><em>How can I check only the changes in one specific file?</em> Say, I have changed files <code>file_1.rb</code>, <code>file_2.rb</code>, ..., <code>file_N.rb</code>, but I am only interested in the changes in the file <code>file_2.rb</code>. How do I check these changes then (before I commit)?</p>