stat命令的实现-mysate（20191213兰毅达）

• 1.提交学习stat（1）的截图
  man 1 stat查看
  
  作用：获取文件信息
  头文件：include <sys/types.h> #include <sys/stat.h> #include <unistd.h>
  函数原型：int stat(const char *path, struct stat *buf)
  返回值：成功返回0，失败返回-1；
  参数：文件路径（名），struct stat 类型的结构体
• 2.man -k ,grep -r的使用
  man -k stat | grep 2查找系统调用
  
  grep -r快速搜索在目录下面的含有关键字的文件
  
• 3.伪代码
  查看并存储文件各个属性
  调用函数stat()
  依次打印输出节点ino、
  文件类型mode、
  文件的连接数nlink、
  用户ID uid和组ID gid、
  块大小blksize、
  字节数size、
  块数目blocks、
  三个时间atime、mtime和ctime
• 4.产品代码 mystate.c

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
    struct stat sb;
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <pathname>
", argv[0]);
        exit(EXIT_FAILURE);
    }
    if (stat(argv[1], &sb) == -1) {
        perror("stat");
        exit(EXIT_FAILURE);
    }
    printf("File type:                ");
    switch (sb.st_mode & S_IFMT) {
        case S_IFBLK:   printf("block device
");
            break;
    case S_IFCHR:   printf("character device
");
            break;
    case S_IFDIR:   printf("directory
");
            break;
    case S_IFIFO:   printf("FIFO/pipe
");
            break;
    case S_IFLNK:   printf("symlink
");
            break;
    case S_IFREG:   printf("regular file
");
            break;
    case S_IFSOCK:  printf("socket
");
            break;
    default:        printf("unknown?
");
            break;
    }
    printf("I-node number:            %ld
", (long) sb.st_ino);
    printf("Mode:                     %lo (octal)
",(unsigned long) sb.st_mode);
    printf("Link count:               %ld
", (long) sb.st_nlink);
    printf("Ownership:                UID=%ld   GID=%ld
",(long) sb.st_uid, (long) sb.st_gid);
    printf("Preferred I/O block size: %ld bytes
",(long) sb.st_blksize);
    printf("File size:                %lld bytes
",(long long) sb.st_size);
    printf("Blocks allocated:         %lld
",(long long) sb.st_blocks);
    printf("Last status change:       %s", ctime(&sb.st_ctime));
    printf("Last file access:         %s", ctime(&sb.st_atime));
    printf("Last file modification:   %s", ctime(&sb.st_mtime));
    exit(EXIT_SUCCESS);
}

码云链接：https://gitee.com/lan_yi_da/codes/kc9e0qigpyadl1hu8245m66

• 5.测试代码，mystat 与stat（1）对比