__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 步骤6：学习并分别使用标准C的文件操作函数和Linux的系统调用创建一个对学生基本信息进行操作（插入、修改和删除）的C程序，学生基本信息以结构体的形式存储在文件stu.info中，struct stu_info的定义如下： struct stu_info { };
char stu_num[12]; char name[10];
short int sex;/*0为女生，1为男生*/ char mobile_phone[12];
3、实验结论
_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
4、程序清单
//程序清单 3-1 #include
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int main(void) { char c; FILE *in,*out;
if((in = fopen(\{ perror(\ exit(0);
}
out = fopen(\
while((c = fgetc(in))!=EOF) fputc(c,out); }
//程序清单 3-2 #include
int main() {
// char block[1024]; char c; int in, out; int nread;
in = open(\
out = open(\//将注释打开，并将两条语句的后一句注释掉，重新编译执行。 // while((nread = read(in,block,sizeof(block))) > 0) while((nread = read(in,&c,sizeof(c))) > 0) // write(out,block,nread); write(out,&c,nread); }
//程序清单 3-3 #include
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#include
char buf1[] = \char buf2[] = \
void err_exit(char *err_s) { perror(err_s); exit(1);
}
int main(void) {
FILE *fp; if((fp = fopen(\
err_exit(\ if(fwrite(buf1,sizeof(buf1),1,fp)!=1)
err_exit(\ if(fseek(fp,40,SEEK_SET)==-1)
err_exit(\ if(fwrite(buf2,strlen(buf2),1,fp)!=1)
err_exit(\ fclose(fp);
}
//程序清单 3-4 #include
char buf1[] = \char buf2[] = \
void err_exit(char *err_s)
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{ perror(err_s); exit(1);
}
int main(void) { int fd; if((fd = open(\
err_exit(\ if(write(fd,buf1,10)!=10)
err_exit(\
if(lseek(fd,40,SEEK_SET)==-1)
err_exit(\ if(write(fd,buf2,10)!=10)
err_exit(\}
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实验四 Linux下进程操作与进程间通信
1、实验目的
（1） 学习和掌握fork等系统调用的基本使用方法。 （2） 利用Linux中的管道实现父子进程间的同步。 2、实验内容与步骤
步骤1：使用Vi将程序清单4-1的程序输入、编译并运行，学习和掌握fork的基本调用方法。
步骤 2：使用Vi将程序清单4-2、4-3和4-4的程序输入、利用gcc分别编译这三个程序，写出编译命令和编译结果，如果不成功，尝试利用gdb调试。
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 步骤3：写出编译这三个程序的makefile,然后利用make进行编译，谈谈这么做的好处。 __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 步骤4：运行这三个程序，写出运行结果。
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 步骤5：屏幕上显示出的执行结果是哪一个进程执行的结果？
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