一、非命名管道

非命名管道适用于父子进程之间通信。

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#include <string.h>
#include <sys/types.h>

int main()
{
	pid_t result;
	int r_num;
	int pipe_fd[2];
	char buf_r[100],buf_w[100];
	memset(buf_r,0,sizeof(buf_r));

	if(pipe(pipe_fd)<0)
	{
		printf("create pipe fail");
		return -1;
	}
	result = fork();//)tu
	if(result < 0)
	{
		printf("create sub procedure fail");
		exit(0);
	}
	else if(result == 0)
	{
		close(pipe_fd[1]);
		if((r_num = read(pipe_fd[0],buf_r,100)) > 0)
			printf("sub procedure %d cha, %s \n",r_num,buf_r);
		close(pipe_fd[0]);
		exit(0);
	}
	else
	{
		close(pipe_fd[0]);
		printf("please input str \n");
		scanf("%s",buf_w);
		if(write(pipe_fd[1],buf_w,strlen(buf_w))!= -1)
			printf("father write: %s\n",buf_w);
		close(pipe_fd[1]);
		waitpid(result,NULL,0);
		exit(0);
	}
}

二、命名管道

进程间通信之FIFO，在阻塞模式下，只有当读和写模式都打开时才返回，否则一直阻塞；

非阻塞模式下，当读端没打开，则打开写端无效，返回错误。

1端

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#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <sys/select.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>

int main()
{
	int i,rfd,wfd,len=0,fd_in;
	char str[32];
	int flag,stdinflag;
	fd_set write_fd,read_fd;
	struct timeval net_timer;
	rfd=open("fifo2",O_RDONLY);
	wfd=open("fifo1",O_WRONLY);  
	if(rfd<=0||wfd<=0) 
	{
		printf("not created!\n");
		mkfifo("fifo1",S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH);
		mkfifo("fifo2",S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH);
		wfd=open("fifo1",O_WRONLY);
		rfd=open("fifo2",O_RDONLY);
	}
	printf("this is 1!\n");
	while(1)
	{
		FD_ZERO(&read_fd);
		FD_SET(rfd,&read_fd);
		FD_SET(fileno(stdin),&read_fd);
		net_timer.tv_sec=5;
		net_timer.tv_usec=0;
		memset(str,0,sizeof(str));
		if(i=select(rfd+1,&read_fd,NULL,NULL,&net_timer)<=0)
			continue;
		if(FD_ISSET(rfd,&read_fd))
		{
			read(rfd,str,sizeof(str));
			printf("--------------\n");
			printf("2:%s\n",str);
		}
		if(FD_ISSET(fileno(stdin),&read_fd))
		{
			printf("--------------\n");
			fgets(str,sizeof(str),stdin);
			len=write(wfd,str,strlen(str));
		}
	}
	close(rfd);
	close(wfd);
}

2端

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#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <sys/select.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>

int main()
{
	int i,rfd,wfd,len=0,fd_in;
	char str[32];
	int flag,stdinflag;
	fd_set write_fd,read_fd;
	struct timeval net_timer;
	wfd=open("fifo2",O_WRONLY);
	rfd=open("fifo1",O_RDONLY);
	if(rfd<=0||wfd<=0) 
	{
		printf("not created!\n");
		mkfifo("fifo1",S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH);
		mkfifo("fifo2",S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH);
		rfd=open("fifo1",O_RDONLY);
		wfd=open("fifo2",O_WRONLY);
	}
	printf("this is 2!\n");
	while(1)
	{
		FD_ZERO(&read_fd);
		FD_SET(rfd,&read_fd);
		FD_SET(fileno(stdin),&read_fd);
		net_timer.tv_sec=5;
		net_timer.tv_usec=0;
		memset(str,0,sizeof(str));
		if(i=select(rfd+1,&read_fd,NULL,NULL,&net_timer)<=0)
			continue;
		if(FD_ISSET(rfd,&read_fd))
		{
			read(rfd,str,sizeof(str));
			printf("--------------\n");
			printf("2:%s\n",str);
		}
		if(FD_ISSET(fileno(stdin),&read_fd))
		{
			printf("--------------\n");
			fgets(str,sizeof(str),stdin);
			len=write(wfd,str,strlen(str));
		}
	}
	close(rfd);
	close(wfd);
}