#include <stdio.h>
#include <unistd.h>
#include <assert.h>
#include <fcntl.h>
#include <sys/types.h>
int main (int argc, char *argv[]) {
int fd = open("/tmp/file", O_WRONLY | O_CREAT | O_TRUNC, S_IRWXU);
assert(fd > -1);
int rc = write(fd, "hello world\n", 13);
assert(rc == 13);
close(fd);
return 0;
}