/**
 **   0   stdin    scanf()    cin     System.in
 **   1   stdout   printf()   cout    System.out
 **   2   stderr   fprintf()  cerr    System.err
 **/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <errno.h>
extern int errno;

int main( int argc, char *argv[] )
{
 if ( argc != 2 )
 {
   fprintf( stderr, "ERROR: Invalid usage.\n" );
   fprintf( stderr, "USAGE: %s <filename>\n", argv[0] );
   return EXIT_FAILURE;
 }

 printf( "Processing file %s....\n", argv[1] );

 int rc = open( argv[1], O_RDONLY );
 if ( rc < 0 )
 {
   fprintf( stderr, "ERROR: errno is %d\n", errno );
   perror( "error opening file" );
   return EXIT_FAILURE;
 }

 return EXIT_SUCCESS;
}