#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/file.h>
#include <unistd.h>

#define FILENAME "testfile"

int main()
{
	int	fd = open( FILENAME, O_RDWR );

	if( fd==0 )
	{
		fputs( "Failed to open `" FILENAME "'.", stderr );
		return 1;
	}

	printf( "flock() returned %d. Now calling close() ...\n",
		flock( fd, LOCK_EX|LOCK_NB ) );
	close( fd );
	return 0;
}