HP Fortran Programmer Guide HP-UX 11i v1, HP-UX 11i v2, and HP-UX 11i v3 (B3908-90032,December 2012)

number. For example, the following open system call (called from a C-language program) opens
a file named DATA.DAT for reading and writing, and returns the value of an HP-UX file descriptor:
#include /* definition of O_RDWR contained here */
fildes = open("DATA.DAT", O_RDWR)
Obtaining an HP-UX file descriptor
The Fortran intrinsic FNUMreturns the HP-UX file descriptor for a given logical unit. See the program
in“File handling” on page 198 for an example of how to call the FNUMintrinsic. For information
about FNUM, see the HP Fortran Programmer's Reference.
Using HP-UX file I/O 107