rtapi_open_as_root - Open a file with "root" privilege

filename
              The  filename to open, as in open(2).  Note that rtapi has no well-defined "current directory", so
              this should be an absolute path, but this is not enforced.

       flags  The open flags, as in open(2).  Should never  include  bits  that  open  or  create  files  (e.g.,
              O_CREAT, O_APPEND, etc) as this API is not intended for creating or writing files, but this is not
              enforced.

       In  "uspace"  realtime,  root privileges are dropped whenever possible.  This API temporarily switches on
       root privileges to open a file, and switches them off before returning.  This can be useful  for  example
       when accessing device nodes or memory-mapped I/O.

       In  the  case of PCI devices on x86 and x86-64 systems, prefer the linux-style PCI interfaces provided in
       <rtapi_pci.h>.

       rtapi_open_as_root - Open a file with "root" privilege

       Call only from realtime initcode in "uspace" realtime.

       In case of success, the nonnegative file descriptor opened.  If the caller does not close it, it  remains
       open until rtapi_app exits.

       In case of failure, a negative errno value.

open(2), rtapi_pci(3)

LinuxCNC Documentation                                                                rtapi_open_as_root(3rtapi)

#include<rtapi.h>intrtapi_open_as_root(constchar*filename,intflags)