title: Linux crontab for nth Satuday of the month
body: <p>I like to run back up for all weekdays except Saturday.
  My crontab entry</p>
  
  <pre><code>30 16 * * 1,2,3,4,5 ./backup.sh
  </code></pre>
  
  <p>This entry working fine.
  Also, I like to take back up on 1st, 3rd Saturday.
  If any 5th Sutarday available in a month then the back up should run. What will be the entry for crontab? I am guessing</p>
  
  <pre><code>30 16 1-7, 15-21, 29-31 * 6 ./backup.sh
  </code></pre>
  
  <p>Am I right?</p>