mkfifo

 1 /*一个应用命名管道进行通信的实例*/
  
　　写端程序

 2 #include<stdio.h>
 3 #include<unistd.h>
 4 #include<stdlib.h>
 5 #include<sys/stat.h>
 6 #include<sys/types.h>
 7 #include<errno.h>
 8 #include<sys/time.h>
 9 #include<time.h>
10 #include<fcntl.h>
11 #include<limits.h>
12 #define BUFES PIPE_BUF
13 
14 int main()
15 {
16     int fd;
17     int n,i;
18     char buf[BUFES];
19 
20     printf("I am process %d\n",getpid());
21     if((fd=open("fifo1",O_WRONLY))<0)    
22     {
23         printf("Open fifo failed!\n");
24         exit(1);
25     }
26     
27     struct timeval tp;
28     struct tm *tm;
29 
30     for(i=0;i<10;i++)
31     {
32         gettimeofday(&tp,NULL);
33         tm=localtime(&tp.tv_sec);    
34         n=sprintf(buf,"write_fifo %d seconds %d-%d-%d %d:%d:%d",getpid(),tm->tm_year+1900,tm->tm_mon+1,tm->tm_mday,tm->tm_hour,tm->tm_min,tm->tm_sec);
35         printf("Send msg:%s\n",buf);
36         if(write(fd,buf,n+1)<0)
37         {
38             printf("Write failed!\n");
39             close(fd);
40             exit(1);
41         }
42         sleep(3);
43     }
44     close(fd);
45     return 0;
46 }

　　读端程序

 1 #include<stdio.h>
 2 #include<unistd.h>
 3 #include<stdlib.h>
 4 #include<sys/stat.h>
 5 #include<sys/types.h>
 6 #include<errno.h>
 7 #include<fcntl.h>
 8 #include<limits.h>
 9 #define BUFES PIPE_BUF
10 
11 int main()
12 {
13     int fd;
14     int i;
15     char buf[BUFES];
16     time_t tp;
17     printf("I am process %d\n",getpid());
18     if((fd=open("fifo1",O_RDONLY))<0)    
19     {
20         printf("Open fifo failed!\n");
21         exit(1);
22     }
23     
24     while(read(fd,buf,BUFES)>0)
25     printf("Read_info read:%s\n",buf);
26     close(fd);
27     return 0;
28 }

程序编译（该程序需要在两个shell中运行）

1 gcc -o write_fifo.c
2 gcc -o read_fifo.c
3 mkfifo -m 666 fifo1
4 ./write_fifo                               //在shell 1中
5 ./read_fifo                                //在shell 2中 

程序执行结果：

 1 shell1中
 2 I am process 10289
 3 Send msg:write_fifo 10289 seconds 2016-2-5 18:44:17
 4 Send msg:write_fifo 10289 seconds 2016-2-5 18:44:21
 5 Send msg:write_fifo 10289 seconds 2016-2-5 18:44:24
 6 Send msg:write_fifo 10289 seconds 2016-2-5 18:44:27
 7 Send msg:write_fifo 10289 seconds 2016-2-5 18:44:30
 8 Send msg:write_fifo 10289 seconds 2016-2-5 18:44:33
 9 Send msg:write_fifo 10289 seconds 2016-2-5 18:44:36
10 Send msg:write_fifo 10289 seconds 2016-2-5 18:44:39
11 Send msg:write_fifo 10289 seconds 2016-2-5 18:44:42
12 Send msg:write_fifo 10289 seconds 2016-2-5 18:44:45
13 
14 
15 shell2中
16 I am process 10288
17 Read_info read:write_fifo 10289 seconds 2016-2-5 18:44:17
18 Read_info read:write_fifo 10289 seconds 2016-2-5 18:44:21
19 Read_info read:write_fifo 10289 seconds 2016-2-5 18:44:24
20 Read_info read:write_fifo 10289 seconds 2016-2-5 18:44:27
21 Read_info read:write_fifo 10289 seconds 2016-2-5 18:44:30
22 Read_info read:write_fifo 10289 seconds 2016-2-5 18:44:33
23 Read_info read:write_fifo 10289 seconds 2016-2-5 18:44:36
24 Read_info read:write_fifo 10289 seconds 2016-2-5 18:44:39
25 Read_info read:write_fifo 10289 seconds 2016-2-5 18:44:42
26 Read_info read:write_fifo 10289 seconds 2016-2-5 18:44:45

并且我们看到如果先打开shell2的时候，其一直在等待shell1发送数据