1 #include <fcntl.h>
 2 #include <unistd.h>
 3 #include <stdio.h>
 4 #include <pthread.h>
 5 #include <string.h>
 6 
 7 pthread_t ntid;
 8 
 9 void * thr_fn(void * arg)
10 {
11    int * fp = (int *)arg;
12    char * str = "Hello the world!\n";
13 
14    int len = write(*fp,str,strlen(str));
15    if(len)
16    {
17     printf("Thread write a string to the file by the descriptor the createprocess created!\n");
18    }
19 
20    close(*fp);
21    return ((void *)0);
22 }
23 
24 int main(void)
25 {
26     int err;
27     int fd;
28 
29     fd = open("log.txt",O_CREAT|O_WRONLY);
30     if(-1 == fd)
31     {
32     printf("Failed to open  file!\n");
33     }
34 
35     err = pthread_create(&ntid,NULL,thr_fn,&fd);
36     if(err != 0)
37     {
38     printf("can‘t create thread ,errno = %d\n",err);    
39     }
40     sleep(3);
41     return 0;
42 }