title: What's file serial number?
body: <p>I found a struct member(name is d_fileno) of 'struct dirent' from <a href="https://www.gnu.org/software/libc/manual/html_node/Directory-Entries.html" rel="nofollow noreferrer">Gnu C library [dirent.h]</a>
  . <br />
  I read documentation but I didn't understand the meaning of file serial number. I couldn't find any satisfactory answer on Google. <br />So, I decided wrote a program to see what looks like the file serial numbers.</p>
  
  <p><strong>Output</strong></p>
  
  <pre><code>$./fileno ..
  file_serial_number   file_name
  [6838726]        [source]
  [6562883]        [..]
  [6838661]        [lstfl]
  [6838718]        [.]
  [6826161]        [research]
  [6838720]        [starcase]
  </code></pre>
  
  <p>So, what's the meaning of these numbers?</p>
  
  <p><strong>Related part from program</strong>:</p>
  
  <pre><code>...
  while((pDirent = readdir(pDir)) != NULL)
      {
        printf("[%li]\t\t [%s]\n",pDirent-&gt;d_fileno, pDirent-&gt;d_name);
      }
  
    closedir(pDir);
  ...
  </code></pre>