stat命令的实现-mysate

struct stat {
    dev_t         st_dev;       //文件的设备编号
    ino_t         st_ino;       //节点
    mode_t        st_mode;      //文件的类型和存取的权限
    nlink_t       st_nlink;     //连到该文件的硬连接数目，刚建立的文件值为1
    uid_t         st_uid;       //用户ID
    gid_t         st_gid;       //组ID
    dev_t         st_rdev;      //(设备类型)若此文件为设备文件，则为其设备编号
    off_t         st_size;      //文件字节数(文件大小)
    unsigned long st_blksize;   //块大小(文件系统的I/O 缓冲区大小)
    unsigned long st_blocks;    //块数
    time_t        st_atime;     //最后一次访问时间
    time_t        st_mtime;     //最后一次修改时间
    time_t        st_ctime;     //最后一次改变时间(指属性)
};

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

int main(int argc, char *argv[])
{
    struct stat sb;
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <pathname>\n", 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\n");
            break;
    case S_IFCHR:   printf("character device\n");
            break;
    case S_IFDIR:   printf("directory\n");
            break;
    case S_IFIFO:   printf("FIFO/pipe\n");
            break;
    case S_IFLNK:   printf("symlink\n");
            break;
    case S_IFREG:   printf("regular file\n");
            break;
    case S_IFSOCK:  printf("socket\n");
            break;
    default:        printf("unknown?\n");
            break;
    }
    printf("I-node number:            %ld\n", (long) sb.st_ino);
    printf("Mode:                     %lo (octal)\n",(unsigned long) sb.st_mode);
    printf("Link count:               %ld\n", (long) sb.st_nlink);
    printf("Ownership:                UID=%ld   GID=%ld\n",(long) sb.st_uid, (long) sb.st_gid);
    printf("Preferred I/O block size: %ld bytes\n",(long) sb.st_blksize);
    printf("File size:                %lld bytes\n",(long long) sb.st_size);
    printf("Blocks allocated:         %lld\n",(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);
}