title: Is there any way to create dummy file descriptor in linux?
body: <p>I have opened one file with following way:</p>
  
  <pre><code>fp = fopen("some.txt","r");
  </code></pre>
  
  <p>Now in this file the 1st some bytes lets say 40 bytes are unnecessary junk of data so I want to remove them. But I cannot delete that data from that file, modify or 
  create duplicates of that file without that unnecessary data. </p>
  
  <p>So I want to create another dummy FILE pointer which points to the file and when I pass this dummy pointer to any another function that does the following operation:</p>
  
  <pre><code>  fseek ( dummy file pointer , 0 , SEEK_SET );
  </code></pre>
  
  <p>then it should set the file pointer at 40th position in my some.txt.</p>
  
  <hr>
  
  <p>But the function accepts a file descriptor so i need to pass a file descriptor which will treat the file as those first 40 bytes were never in the file.</p>
  
  <hr>
  
  <p>In short that dummy descriptor should treat the file as those 40 bytes were not in that file and all positioning operations should be with respect to that 40th byte counting as the is 1st byte.</p>