/sys$common/syshlp/helplib.hlb CC, Run-time functions, fdopen  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Associates a file pointer with a file descriptor returned by an
  open, creat, dup, dup2, or pipe function.

  Syntax:

       #include <stdio.h>

       FILE *fdopen(int file_descriptor, char *a_mode);