title: AWK - replace specific column on matching line, then print other lines
body: <p>I am trying to alter a column/field within a 'header' line of DNA sequences that is thousands of lines long.  Specifically, I want to change the first field of the header (compX_seqy), which ALWAYS starts with ">":</p>
  
  <p>An example of just the first two sequences: </p>
  
  <pre><code> #cat example
  
   &gt;comp0_seq1 444 [12:23]
   AGAGGACAC
   GATCCAACATA
   AGASCAC
   &gt;comp0_seq2 333 [12:32:599:1]
   GTCGATC
   CYAACY
   CCCCA
   ...
  </code></pre>
  
  <p>I would like to add an "A" to the end of the first column only,  for ALL lines starting with ">",</p>
  
  <blockquote>
    <p>comp0_seq1A</p>
  </blockquote>
  
  <p>Then print the rest of the line and then next lines (sequences) until the next ">" line is reached (and repeat).</p>
  
  <p>I want the output to look like this :</p>
  
  <pre><code>&gt;comp0_seq1A 444 [12:23]
  AGAGGACAC
  GATCCAACATA
  AGASCAC
  &gt;comp0_seq2A 333 [12:32:599:1]
  GTCGATC
  CYAACY
  CCCCA
  ...
  </code></pre>
  
  <p>I tried this first:</p>
  
  <pre><code>awk '$1=$1"A"' example
  
  &gt;comp0_seq1A 444 [12:23]
  AGAGGACACA
  GATCCAACATAA
  AGASCACA
  &gt;comp0_seq2A 333 [12:32:599:1]
  GTCGATCA
  CYAACYA
  CCCCAA
  A
  A
  </code></pre>
  
  <p>It adds an A to the first field of all lines, So not quite.</p>
  
  <p>Then I tried this, using a regex to replace only lines starting with ">"</p>
  
  <pre><code># awk '/^&gt;/ {print $1=$1"A";getline;print $0}' example
  &gt;comp0_seq1A
  AGAGGACAC
  &gt;comp0_seq2A
  GTCGATC
  </code></pre>
  
  <p>But that only prints the first line AFTER the match. So, how to print all/any lines AFTER the match/replacement, and until the next ">"?  I tried to use 'next', but I guess I dont understand how to use it in this context.</p>
  
  <p>Any advice? I know I am close and am banging my head on my keyboard.</p>
  
  <p>Thx, LP.</p>