pipe()函数在子进程产生之前就应该存在。
- 父子进程之间只进行一次传递
/*============================================
> Copyright (C) 2014 All rights reserved.
> FileName：onepipe.c
> author：donald
> details：
==============================================*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 512
int main(int argc, const char *argv[])
{
int pipefd[];
pid_t pid; if(pipe(pipefd) == -){
perror("pipe failed");
exit(-);
}
printf("%u\n",pid);
pid == fork();//这里一个个大大的bug，自己的误操作，debug了很久才搞定了
printf("%u\n",pid);
if( == pid){
close(pipefd[]);//0 read 1 write
//一个约定，父子进程都需遵守 char buf[N];
memset(buf,,N);
read(pipefd[],buf,N);
printf("child read:%s\n",buf); printf("child exit\n");
exit();
}else{
close(pipefd[]);//0 read
char line[N];
printf("parent begin\n"); memset(line,,N);
fgets(line,N,stdin); write(pipefd[],line,strlen(line));
printf("parent exit\n");
wait(NULL);//等待子进程的结束
}
return ;
} -
父子进程通过管道，进行多次读写操作，先贴上一个比较奇葩的方法（就是一个错误）：
/*============================================
> Copyright (C) 2014 All rights reserved.
> FileName：my_pipe.c
> author：donald
> details：
==============================================*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 1024
int main(int argc, const char *argv[])
{
int fds[];
if(pipe(fds) == -){//只能有一对进行读写
perror("failed");
exit();
}
pid_t pid = fork();
if(pid == -){
perror("error");
exit();
} while(){
if(pid == ){//child read
close(fds[]);//1 write
char buf[] = "";
read(fds[],buf,);//只能有一个读，
printf("child read:%s\n",buf);
//exit(1);
}else{//parent write close(fds[]);//0 read
// char *p = "hello,donald";
char line[N];
// memset(line,0,N);
fgets(line,N,stdin);
write(fds[],line,strlen(line));
//wait(NULL);
}
}
return ;
}再贴上正确的方法：
/*============================================
> Copyright (C) 2014 All rights reserved.
> FileName：twopipe.c
> author：donald
> details：
==============================================*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 512
int main(int argc, const char *argv[])
{
int pipefd[];
pid_t pid;
//pid = fork(); if(pipe(pipefd) == -){
perror("pipe failed");
exit(-);
}
pid = fork();
if(pid == ){
close(pipefd[]);//0 read
char buf[N];
while(){
memset(buf,,N);
if(read(pipefd[],buf,N) == ){
break;
}
printf("child read:%s\n",buf);
}
printf("child exit\n");
exit();
}else{
close(pipefd[]);
char line[N];
while(memset(line,,N),fgets(line,N,stdin) != NULL ){
write(pipefd[],line,strlen(line));
}
close(pipefd[]);
printf("parent exit\n");
wait(NULL);
}
return ;
}