title: Where is the tell() function defined?
body: <p>Can you please tell me where the <strong>off_t tell(int fd)</strong> function is defined in <strong>Mac OS X</strong>? It's not in <strong>fcntl.h</strong> and not in <strong>unistd.h</strong>, where it is defined in <strong>UNIX</strong>... I can't use <strong>ftell()</strong> because the code I'm porting works with file descriptors.</p>
  
  <p>I'm using GCC v4.2.1</p>