title: Repeating jobs of sequential file names
body: <p>If I have <code>sample_1.txt</code>, <code>sample_2.txt</code>, <code>sample_3.txt</code>, <code>sample_4.txt</code>, and I want to perform a command line job repeatedly. </p>
  
  <p>For example, instead of typing the same command four times like below, is there a command that could do that automatically? </p>
  
  <pre><code>$ grep 'pattern' sample_1.txt
  $ grep 'pattern' sample_2.txt
  $ grep 'pattern' sample_3.txt
  $ grep 'pattern' sample_4.txt
  </code></pre>