text: user4712: I need to find the following pattern from a genomic sequence
  TTCGB-N15-TTCGB
  B represents C, G, or T
  N15 represents A, T, G or C and these four base combination should have the length of 15 bases.
  
  To do the same, I tried grep command, but I could not specify B and N15 in the grep command line. Therefore, please help me to find the same.
  For example, I have a nucleotide sequences as follows
  >ATGCTTATTGCCCATTTCGTGCATGCATATGCGCATTCGCGATCGATTAGGGATAT
  
  Expected outcome,
  
  TTCGTGCATGCATATGCGCATTCGC
  
  Thanks in advance.  
  
  user3541: echo ">ATGCTTATTGCCCATTTCGTGCATGCATATGCGCATTCGCGATCGATTAGGGATAT" | grep -oP  'TTCG[CGT][ATGC]{1,15}TTCG[CGT]'
  
  
  [CGT] looks for one occurrence of one of the three.
  [ATGC]{1,15} looks for "up to 15 letter long" combinations of the four bases.
  
  Moreover, -P makes your regex call Perl-like and is required to make this regex work. Different regex flavors behave (slightly) differently.
  
original_text: 4712: <p>I need to find the following pattern from a genomic sequence</p>
  
  <pre><code>TTCGB-N15-TTCGB
  B represents C, G, or T
  N15 represents A, T, G or C and these four base combination should have the length of 15 bases.
  </code></pre>
  
  <p>To do the same, I tried <code>grep</code> command, but I could not specify <code>B</code> and <code>N15</code> in the <code>grep</code> command line. Therefore, please help me to find the same.</p>
  
  <p>For example, I have a nucleotide sequences as follows</p>
  
  <pre><code>&gt;ATGCTTATTGCCCATTTCGTGCATGCATATGCGCATTCGCGATCGATTAGGGATAT
  </code></pre>
  
  <p>Expected outcome,</p>
  
  <blockquote>
    <p>TTCGTGCATGCATATGCGCATTCGC</p>
  </blockquote>
  
  <p>Thanks in advance.  </p>
   3541: <pre><code>echo "&gt;ATGCTTATTGCCCATTTCGTGCATGCATATGCGCATTCGCGATCGATTAGGGATAT" | grep -oP  'TTCG[CGT][ATGC]{1,15}TTCG[CGT]'
  </code></pre>
  
  <ul>
  <li><code>[CGT]</code> looks for one occurrence of one of the three.</li>
  <li><code>[ATGC]{1,15}</code> looks for "up to 15 letter long" combinations of the four bases.</li>
  </ul>
  
  <p>Moreover, <code>-P</code> makes your regex call <code>Perl-like</code> and is required to make this regex work. Different regex flavors behave (slightly) differently.</p>
  