linux 管道

#include <unistd.h>
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
//管道通讯：单向，先进先出，管道尾部写入数据，管道头部读出数据；数据读出后，管道将自动删除该数据；
//无名管道，用于父子进程间通讯，先创建管道，再fork创建子进程，该子进程继承父进程创建的管道；
// 管道创建 int pipe(int filedis[2]); 管道关闭close（filedis[2]);
int main()
{
int pipe_fd[2];
pid_t pid;
char buf[100];
int readnum,writenum;

memset(buf,0,100);//清buf

if(pipe(pipe_fd)<0)
{
printf("creat pipe failure!\n");
exit(1);
}
else
printf("creat pipe success!\n");

if((pid=fork())==0)//子进程
{
close(pipe_fd[1]);//关闭管道尾部（管道写）
if((readnum=read(pipe_fd[0],&buf,6))>0)
printf("read pipe success,number=%d,data=%s\n",readnum,buf);
else if(readnum==0)
printf("pipe is empty!\n");
else
printf("read pipe failure!\n");

if((readnum=read(pipe_fd[0],&buf,15))>0)
printf("read pipe success,number=%d,data=%s\n",readnum,buf);
else if(readnum==0)
printf("pipe is empty!\n");
else
printf("read pipe failure!\n");

close(pipe_fd[0]);//关闭管道头部，管道读结束

exit(0);
}
else if(pid>0)
{
close(pipe_fd[0]);//关闭管道头部（管道读）
if((writenum=write(pipe_fd[1],"delta electronic ",17))>0)
printf("write pipe success!,number=%d,data=%s\n",writenum,"delta electronic ");
else
printf("write pipe failure!\n");

if((writenum=write(pipe_fd[1],"will",4))>0)
printf("write pipe success!,number=%d,data=%s\n",writenum,"will");
else
printf("write pipe failure!\n");

close(pipe_fd[1]);//关闭管道尾部，管道写结束
waitpid(pid,NULL,0);//等待子进程结束
exit(0);
}
exit(0);
}