实现stat命令

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

int main(int argc,char* argv[])
{
if(argc<2)
{
printf("./mystat filename\n");
exit(1);
}
// 文件信息结构体
struct stat st;

int ret = stat(argv[1],&st);
if(ret == -1)
{
perror("stat");
exit(1);
}

//存储文件类型和访问权限
char perms[11] = { 0 };
//判断文件类型
switch(st.st_mode & S_IFMT)
{
case S_IFLNK:
perms[0] = 'l';
break;
case S_IFDIR:
perms[0] = 'd';
break;
case S_IFREG:
perms[0] = '-';
break;
case S_IFBLK:
perms[0] = 'b';
break;
case S_IFSOCK:
perms[0] = 's';
break;
case S_IFIFO:
perms[0] = 'f';
break;
default:
perms[0] = '?';
break;
}

//判断文件的访问属性
//文件所有者
perms[1] = (st.st_mode & S_IRUSR) ? 'r':'-';
perms[2] = (st.st_mode & S_IWUSR) ? 'w':'-';
perms[3] = (st.st_mode & S_IXUSR) ? 'x':'-';

//判断所有组
perms[4] = (st.st_mode & S_IRGRP) ? 'r':'-';
perms[5] = (st.st_mode & S_IWGRP) ? 'w':'-';
perms[6] = (st.st_mode & S_IXGRP) ? 'x':'-';

//判断其他人
perms[7] = (st.st_mode & S_IROTH) ? 'r':'-';
perms[8] = (st.st_mode & S_IWOTH) ? 'w':'-';
perms[9] = (st.st_mode & S_IXOTH) ? 'x':'-';

//硬链接计数
int linkNum = st.st_nlink;
//文件所有者
char* fileUser = getpwuid(st.st_uid)->pw_name;
//文件所属组
char* fileGrp = getgrgid(st.st_gid)->gr_name;
//文件大小
int fileSize = st.st_size;
//修改时间
char* time = ctime(&st.st_mtime);
char mtime[512] = {0};
strncpy(mtime,time,strlen(time)-1);

char buf[1024];

sprintf(buf,"%s %d %s %s %d %s %s %s",perms,linkNum,fileUser,fileGrp,fileSize,mtime,argv[1]);

printf("%s\n",buf);
return 0;

}