进程 day1-优快云博客

该程序是用C语言编写的，用于在Ubuntu系统中通过父子进程协同工作来拷贝文件。程序首先检查命令行参数，然后打开源文件和目标文件。父进程读取源文件的一半内容并写入目标文件，子进程处理剩余的一半。文件操作包括使用open(),read(),write(),lseek()等系统调用，并确保正确处理错误情况。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

作业：用父子进程拷贝文件：

ubuntu@ubuntu:~$ cat test6.c
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>

int main(int argc,char *argv[])
{
if(argc!=3)//argv[1]:源文件；argv[2]:目标文件
{
perror("You Wrong");
return -1;
}
int myread=open(argv[1],O_RDONLY);
if(myread<0)
return -1;
int mywrite=open(argv[2],O_WRONLY|O_CREAT,0664);
if(mywrite<0)
return -1;
int len=lseek(myread,0,SEEK_END);

int count=0;
char buf[128];
pid_t pid=fork();

if(pid<0)
exit(-1);
else if(pid==0)
{

/*int myread=open(argv[1],O_RDONLY);
if(myread<0)
   return -1;
int mywrite=open(argv[2],O_WRONLY|O_CREAT,0664);
if(mywrite<0)
   return -1;*/
   lseek(myread,0,SEEK_SET);
   lseek(mywrite,0,SEEK_SET);
while(count<=len/2)
{
int cread=read(myread,buf,sizeof(buf));
count=count+cread;
if(count>len/2)
   write(mywrite,buf,cread-(count-len/2));
else
   write(mywrite,buf,cread);
bzero(buf,sizeof(buf));
}
}
else
{
wait(NULL);
lseek(myread,len/2+1,SEEK_SET);
lseek(mywrite,len/2+1,SEEK_SET);
count=len/2;
while(count<=len)
{
int myr=read(myread,buf,sizeof(buf));
   count=count+myr;
   write(mywrite,buf,sizeof(buf));
bzero(buf,sizeof(buf));
}