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