Question

Linux下进程的创建与进程间通信

编制一段程序，实现进程间的管道通信。使用系统调用pipe()建立一条管道，两个子进程p1和p2分别向通道各写一句话：
The first child process is sending message!
The second child process is sending message!

而父进程则从管道中读出来自两个进程的信息，显示在屏幕上。

示例
int fd[2];
char outpipe[100],inpipe[100];
pipe(fd); /*创建一个管道*/
write(fd[1],outpipe,100); /*向管道写长为100字节的串*/
read(fd[0],inpipe,100); /*从管道中读长为100字节的串*/

互斥访问管道
锁管道：lockf(fd[1], 1, 0)
管道解锁：lockf(fd[1], 0, 0)
C语言

Answer 1

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

int main()
{
int fd[2], pid, len;
char inpipe[100], outpipe[100];

pipe(fd);

pid = fork();

if (pid == 0)
{
/* first child */
close(fd[0]);
strcpy(outpipe, "The first child process is sending message!");
lockf(fd[1], 1, 0);
write(fd[1], outpipe, 100);
lockf(fd[1], 0, 0);
exit(0);
}

pid = fork();
if (pid == 0)
{
/* 2nd child */
close(fd[0]);
strcpy(outpipe, "The second child process is sending message!");
lockf(fd[1], 1, 0);
write(fd[1], outpipe, 100);
lockf(fd[1], 0, 0);
exit(0);
}

/* parent */
close(fd[1]);
len = read(fd[0], inpipe, 100);
printf("RECV: %s\n", inpipe);

len = read(fd[0], inpipe, 100);
printf("RECV: %s\n", inpipe);

wait(NULL);
wait(NULL);
return 0;
}