多进程思维导图

1> 思维导图

2> 使用父子进程完成两个文件的拷贝，父进程拷贝前一半，子进程拷贝后一半，两个进程同时进行（君子作业）

#include <myhead.h>
typedef struct sockaddr_in addr_in_t;
typedef struct sockaddr addr_t;
typedef struct sockaddr_un addr_un_t;void zijincheng(int wfd,int rfd,int guang_biao){lseek(wfd,guang_biao/2,SEEK_SET);lseek(rfd,guang_biao/2,SEEK_SET);char ch ;for(int i=0;i<guang_biao/2;i++){int res = read(rfd,&ch,1);write(wfd,&ch,1);//if()abreak;}exit(0);}
int main(int argc, const char *argv[])
{pid_t pid = fork();	int wfd = open(argv[2],O_WRONLY|O_CREAT|O_TRUNC,0664);if(wfd==-1){perror("write err:");}int rfd = open(argv[1],O_RDONLY);if(rfd==-1){perror("read err:");}int guang_biao = lseek(rfd,0,SEEK_END);if(pid == 0){zijincheng(wfd,rfd,guang_biao);//exit(0);}char ch;lseek(rfd,0,SEEK_SET);for(int i=0;i<guang_biao/2;i++){read(rfd,&ch,1);write(wfd,&ch,1);//	if(res == 0)break;}wait(NULL);return 0;
}