linux管道学习（二）

 1 int main()
 2 {
 3     char* pipename = "pipe";
 4     mkfifo(pipename,0777);
 5     int pid = fork();
 6     if(pid < 0)
 7     {
 8         printf("Error In Fork\n");
 9         exit(-1);
10     }
11
12     if(pid == 0)
13     {
14         printf("In Child Process\n");
15         int fd = open(pipename,O_WRONLY|O_NONBLOCK);
16         node testnode;
17         testnode.a = 10;
18         testnode.b = 20;
19
20         write(fd,&testnode,sizeof(testnode));
21
22         testnode.a = 11;
23         testnode.b = 22;
24
25         write(fd,&testnode,sizeof(testnode));
26
27         close(fd);
28         printf("Child Process Is Over \n");
29     }
30     if(pid > 0)
31     {
32
33         printf("In Parent Process\n");
34
35         int fd = open(pipename,O_RDONLY);
36
37         node testnode;
38         read(fd,&testnode,sizeof(node));
39         printf("Msg From Child node a = %d,b = %ld \n",testnode.a,testnode.b);
40
41         read(fd,&testnode,sizeof(node));
42         printf("Msg From Child node a = %d,b = %ld \n",testnode.a,testnode.b);
43
44         close(fd);
45
46         waitpid(pid,NULL,0);
47         printf("Praent Process Is Over \n");
48     }
49
50
51 }

在阻塞情况下，管道会阻塞直到有内容写入

读取时如果管道为空会等待有内容可以读取

在打开管道的时候可以选择非阻塞方式O_NONBLOCK

如果是非阻塞方式则忽略当前管道状态

命名管道不仅可以在有亲缘关系的进程中进行通信，也可以在无亲缘关系的进程中通信。