POSIX IO的应用.doc

实验五 POSIX IO的应用班级 B08512 姓名 张一梦 学号 20084051211 日期 2011/3/25 成绩评定 1实验目的（1）掌握Linux系统中文件的创建、打开、关闭、读、写等函数的使用（2）掌握open、read、write、fcntl等系统调用的使用（3）掌握readdir、mkdir、rmdir、getcwd、get_current_dir_name等对目录文件的操作函数2实验环境已安装Linux操作系统的微机一台3实验内容（1）阅读程序，了解系统调用open、creat、read、write等系统的使用#include #include #include #include #include #include int main()int fd;if (fd = open(example_62.c, O_CREAT|O_EXCL, S_IRUSR| S_IWUSR) = -1) /if (fd = creat(example_62.c, S_IRWXU) = -1) perror(open); /printf(open:%s with errno:%dn,strerror(errno),errno);exit(1); else printf(create file successn);close(fd);return 0;程序运行结果：使用open 运行结果如图1所示，使用creat 运行结果如图1所示图1 open 运行结果图2 creat 运行结果回答问题：open与creat的异同点。#include #include #include #include #include #include /*自定义的错误处理函数*/void my_err(const char * err_string, int line)fprintf(stderr, line:%d , line);perror(err_string);exit(1);/*自定义的读数据函数*/int my_read(int fd)intlen;intret;inti;charread_buf64;/*获取文件长度并保持文件读写指针在文件开始处*/if (lseek(fd, 0, SEEK_END) = -1) my_err(lseek, _LINE_);if (len = lseek(fd, 0, SEEK_CUR) = -1) my_err(lseek, _LINE_);if (lseek(fd, 0, SEEK_SET) = -1) my_err(lseek, _LINE_);printf(len:%dn, len);/*读数据*/if (ret = read(fd, read_buf, len) 0) my_err(read, _LINE_);/*打印数据*/for (i=0; ilen; i+) printf(%c, read_bufi);printf(n);return ret;int main()intfd;char write_buf32 = Hello World!;/*在当前目录下创建文件example_63.c*/if (fd = creat(example_63.c, S_IRWXU) = -1) if (fd = open(example_63.c, O_RDWR|O_CREAT|O_TRUNC, S_IRWXU) = -1) my_err(open, _LINE_); else printf(create file successn);/*写数据*/if (write(fd, write_buf, strlen(write_buf) != strlen(write_buf) my_err(write, _LINE_);my_read(fd);/*演示文件的间隔*/printf(/*-*/n);if (lseek(fd, 10, SEEK_END) = -1) my_err(lseek, _LINE_);if (write(fd, write_buf, strlen(write_buf) != strlen(write_buf) my_err(write, _LINE_);my_read(fd);close(fd);return 0;程序运行结果如图3所示：图3 运行结果回答问题：read、write、lseek等函数的作用。（2）程序设计 在a目录文件中编写程序，实现在屏幕上显示当前文件所在路径、显示a目录中的所有文件名及文件内容。如：当前路径为：/home/aa. txt:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaapress enter to continueb.txt:bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbpress enter to continueend源代码：#include#include#include#include#include#includeint main(int argc,char *argv)char *p;p=getcwd(NULL,128);printf(current path:%sn,p);free(p);DIR *dirp;struct dirent *dp1=malloc(sizeof(struct dirent);struct dirent *dp2=malloc(sizeof(struct dirent);dirp=opendir(.);while(1)if(readdir_r(dirp,dp1,&dp2)!=0)perror(readdir);exit(0);if(dp2=NULL)break;if(dp2-d_name0=.)continue;printf(dname=%sn,dp2-d_name);int fd,fd1,num,i;char buf128;if(fd=open(dp2-d_name,O_RDONLY)=-1)perror(file open failuren);exit(0);donum=read(fd,buf,128); for (i=0;inum; i+) printf(