title: SPRINTF in shell scripting?
body: <p>I have an auto-generated file each day that gets called by a shell script. 
  But, the problem I'm facing is that the auto-generated file has a form of:  </p>
  
  <pre><code>FILE_MM_DD.dat
  </code></pre>
  
  <p>... where MM and DD are 2-digit month and day-of-the-month strings.</p>
  
  <p>I did some research and banged it at on my own, but I don't know how to create these custom strings using only shell scripting.  </p>
  
  <p>To be clear, I am aware of the DATE function in Bash, but what I'm looking for is the equivalent of the SPRINTF function in C.</p>