title: Edit text columns
body: <p>I have a text file (the first two lines are character spacings):</p>
  
  <blockquote>
  <pre><code>         1         2         3         4         5         6         7         8
  12345678901234567890123456789012345678901234567890123456789012345678901234567890
  ATOM      1  N1  SPINA   3      30.616  29.799  14.979  1.00 20.00      S    N  
  ATOM      2  N1  SPINA   3      28.146  28.381  13.950  1.00 20.00      S    N  
  ATOM      3  N1  SPINA   3      27.605  28.239  14.037  1.00 20.00      S    N  
  ATOM      4  N1  SPINA   3      30.333  29.182  15.464  1.00 20.00      S    N  
  ATOM      5  N1  SPINA   3      29.608  29.434  14.333  1.00 20.00      S    N  
  ATOM      6  N1  SPINA   3      29.303  29.830  13.317  1.00 20.00      S    N  
  ATOM      7  N1  SPINA   3      28.963  31.116  13.472  1.00 20.00      S    N  
  ATOM      8  N1  SPINA   3      28.859  28.743  13.828  1.00 20.00      S    N  
  ATOM      9  N1  SPINA   3      29.699  30.575  14.564  1.00 20.00      S    N  
  ATOM     10  N1  SPINA   3      29.518  29.194  15.301  1.00 20.00      S    N
  </code></pre>
  </blockquote>
  
  <p>I want to edit it and make it like:</p>
  
  <blockquote>
  <pre><code>         1         2         3         4         5         6         7         8
  12345678901234567890123456789012345678901234567890123456789012345678901234567890
  ATOM      1 N001 SPINA   3      30.616  29.799  14.979  1.00 20.00      S    N  
  ATOM      2 N002 SPINA   3      28.146  28.381  13.950  1.00 20.00      S    N  
  ATOM      3 N003 SPINA   3      27.605  28.239  14.037  1.00 20.00      S    N  
  ATOM      4 N004 SPINA   3      30.333  29.182  15.464  1.00 20.00      S    N  
  ATOM      5 N005 SPINA   3      29.608  29.434  14.333  1.00 20.00      S    N  
  ATOM      6 N006 SPINA   3      29.303  29.830  13.317  1.00 20.00      S    N  
  ATOM      7 N007 SPINA   3      28.963  31.116  13.472  1.00 20.00      S    N  
  ATOM      8 N008 SPINA   3      28.859  28.743  13.828  1.00 20.00      S    N  
  ATOM      9 N009 SPINA   3      29.699  30.575  14.564  1.00 20.00      S    N  
  ATOM     10 N010 SPINA   3      29.518  29.194  15.301  1.00 20.00      S    N
  </code></pre>
  </blockquote>
  
  <p>The number of spaces between each column are important and the list of atoms needs to go up to 190 (N001-N190). Thus I would like to replace characters 13-16 (" N1 ") in file 1 with ("N001") and keep the remainder of the file in the original spacing.</p>