1、使用两个进程完成两个文件的拷贝，父进程拷贝前一半内容，子进程拷贝后一半内容，并且父进程要阻塞回收子进程资源

#include <myhead.h>int main(int argc, const char *argv[])
{char a[1] = {0};pid_t pid;pid = fork();//创建一个子进程int src = open(argv[1],O_RDONLY);if(src < 0){perror("open error");return -1;}int dest = open(argv[2],O_RDWR|O_CREAT|O_TRUNC,0666);if(dest < 0){perror("open error");return -1;}//计算机读取文件的字符个数int size = lseek(src,0,SEEK_END)-lseek(src,0,SEEK_SET);int halfsize = size / 2;ssize_t s;//开始打印if(pid < 0){perror("fork error");return -1;}else if(pid == 0)//子进程{lseek(src,1,SEEK_SET);lseek(dest,1,SEEK_SET);for(int i = 0; i<halfsize; i++){s = read(src,a,1);write(dest,a,s);}}else//父进程{lseek(src,0,SEEK_SET);lseek(dest,0,SEEK_SET);for(int i = 0; i<halfsize; i++){s = read(src,a,1);write(dest,a,s);}//阻塞等待回收子进程资源wait(NULL);}return 0;
}

2、使用三个进程完成两个文件的拷贝，父进程拷贝前三分之一，子进程1拷贝中间三分之一，子进程2拷贝后三分之一，父进程要阻塞回收所有子进程资源

#include <myhead.h>int main(int argc, const char *argv[])
{char a[1] = {0};pid_t pid;pid = fork();//创建一个子进程int src = open(argv[1],O_RDONLY);if(src < 0){perror("open error");return -1;}int dest = open(argv[2],O_RDWR|O_CREAT|O_TRUNC,0666);if(dest < 0){perror("open error");return -1;}
//计算机读取文件的字符个数int size = lseek(src,0,SEEK_END)-lseek(src,0,SEEK_SET);int len = size / 3;ssize_t s;//开始打印if(pid < 0){perror("fork error");return -1;}else if(pid == 0)//子进程{lseek(src,1,SEEK_SET);lseek(dest,1,SEEK_SET);for(int i = 0; i<len; i++){s = read(src,a,1);write(dest,a,s);}}else{pid_t pid2 = fork();//在父进程中再创建一个子进程if(pid2 < 0){perror("fork error");return -1;}else if(pid2 == 0){lseek(src,2,SEEK_SET);lseek(dest,2,SEEK_SET);for(int i = 0; i<len; i++){s = read(src,a,1);write(dest,a,s);}}else//父进程{lseek(src,0,SEEK_SET);lseek(dest,0,SEEK_SET);for(int i = 0; i<len; i++){s = read(src,a,1);write(dest,a,s);}//阻塞等待回收子进程资源wait(NULL);wait(NULL);}}return 0;
}

3、思维导图