title: Sorting and Uniq
body: <p>I have a file that I'm trying to sort based on the fourth column and removing duplicate lines based on that column as well. My file looks like this after I used <code>sort -uk4,4</code>:</p>
  
  <pre><code>chr1    76190472    76190502    NM_000016_cds_0_0_chr1_76190473_f   0   +
  chr1    76226806    76227055    NM_000016_cds_10_0_chr1_76226807_f  0   +
  chr1    76228376    76228448    NM_000016_cds_11_0_chr1_76228377_f  0   +
  chr1    76194085    76194173    NM_000016_cds_1_0_chr1_76194086_f   0   +
  chr1    76198328    76198426    NM_000016_cds_2_0_chr1_76198329_f   0   +
  chr1    76198537    76198607    NM_000016_cds_3_0_chr1_76198538_f   0   +
  chr1    76199212    76199313    NM_000016_cds_4_0_chr1_76199213_f   0   +
  chr1    76200475    76200556    NM_000016_cds_5_0_chr1_76200476_f   0   +
  chr1    76205664    76205795    NM_000016_cds_6_0_chr1_76205665_f   0   +
  chr1    76211490    76211599    NM_000016_cds_7_0_chr1_76211491_f   0   +
  chr1    76215103    76215244    NM_000016_cds_8_0_chr1_76215104_f   0   +
  chr1    76216135    76216231    NM_000016_cds_9_0_chr1_76216136_f   0   +
  </code></pre>
  
  <p>However, the function has not sorted as a I would prefer because after the <code>_cds_</code> in the fourth column I would like the numbers in descending order: 0, 1, 2, 3...etc instead of 0, 10, 11, 1. Is there any way to do such a thing?  </p>