title: Output 64 bit integer with hexdump
body: <p>I currently work on some binary data.
  In order to check and debug the data previously generated by my application I use <em>hexdump</em>, facing the obstacle of hexdump not appearing to be able to extract a 64-bit integer field.
  Given the following minimal example:</p>
  
  <pre><code>#include &lt;iostream&gt;
  #include &lt;fstream&gt;
  #include &lt;cstdint&gt;
  
  int main(int argc, char** argv){
      std::ofstream os("tmp.bin", std::ios::out | std::ios::binary);
      uint64_t x = 7;
      os.write((char*)&amp;x,sizeof(uint64_t));
      os.close();
      return 0;
  }
  </code></pre>
  
  <p>I perform a simple hexdump on my system:</p>
  
  <pre><code>hexdump tmp.bin
  
  &gt; 0000000: 0007 0000 0000 0000
  &gt; 0000008:
  </code></pre>
  
  <p>Now trying to extract the unsigned int of 64 bit width yields:</p>
  
  <pre><code>hexdump -e '/8 "%u"' tmp.bin
  
  &gt; hexdump: bad byte count for conversion character u
  </code></pre>
  
  <p>According to the well written <a href="https://www.suse.com/communities/conversations/making-sense-hexdump/" rel="noreferrer">hexdump-manual by <em>David Mair</em></a> it should be possible to do it, but I have no success.</p>
  
  <p>What am I missing ?</p>