（二）和菜鸟一起学unix之文件和目录 stat

man  2 stat

 

STAT(2)                    Linux Programmer’s Manual                   STAT(2)

NAME
       stat, fstat, lstat - get file status

SYNOPSIS
    //头文件
       #include <sys/types.h>
       #include <sys/stat.h>
       #include <unistd.h>

       int stat(const char *path, struct stat *buf);
       int fstat(int filedes, struct stat *buf);
       int lstat(const char *path, struct stat *buf);
     参数path  文件路路径名称  buf 结构体的指针
DESCRIPTION
       These  functions  return  information about a file.  No permissions are
       required on the file itself, but — in the case of stat() and lstat()  —
       execute  (search)  permission  is required on all of the directories in
       path that lead to the file.

       stat() stats the file pointed to by path and fills in buf.
                  
       lstat() is identical to stat(), except that if path is a symbolic link,
       then the link itself is stat-ed, not the file that it refers to.

       fstat()  is  identical to stat(), except that the file to be stat-ed is
       specified by the file descriptor filedes.

  All of these system calls return a stat structure, which  contains  the
       following fields:

          struct stat {
              dev_t     st_dev;     /* ID of device containing file */
              ino_t     st_ino;     /* inode number */
              mode_t    st_mode;    /* protection */
              nlink_t   st_nlink;   /* number of hard links */
              uid_t     st_uid;     /* user ID of owner */
              gid_t     st_gid;     /* group ID of owner */
              dev_t     st_rdev;    /* device ID (if special file) */
              off_t     st_size;    /* total size, in bytes */
              blksize_t st_blksize; /* blocksize for filesystem I/O */
              blkcnt_t  st_blocks;  /* number of blocks allocated */
              time_t    st_atime;   /* time of last access */
              time_t    st_mtime;   /* time of last modification */
              time_t    st_ctime;   /* time of last status change */
          };
 返回值  3个函数的返回值：成功返回 0 失败返回 -1；
     宏：
 struct stat buf;
 lstat("路径",&buf);
 S_ISREG();普通文件
 S_ISDIR();目录文件
 S_ISCHR();字符设备
 S_ISBLK();块设备
 S_ISFIFO();管道
 S_ISLNK()；链接
 S_ISSOCK()套接字
 例子：
 
 #include <stdlib.h>
#include <stdio.h>
int main(int argc,char *argv[])
{
 int i;
 struct stat buf;
 char *ptr;
 for(i=1;i<argc;i++)
 {
  printf("%s: ",argv[i]);
  if(lstat(argv[i],&buf)<0)
  {
   perror("lstat");
   continue;
  }
  if(S_ISREG(buf.st_mode))
   ptr = "regular file";
  else if(S_ISDIR(buf.st_mode))
   ptr = "directory file";
  else if(S_ISCHR(buf.st_mode))
   ptr = "character special file";
  else if(S_ISBLK(buf.st_mode))
   ptr = "block special file";
  else if(S_ISFIFO(buf.st_mode))
   ptr = "FIFO file";
  else if(S_ISLNK(buf.st_mode))
   ptr = "link file";
  else if(S_ISSOCK(buf.st_mode))
   ptr = "socket file";
  printf("%s\n",ptr);
 }
 return 0;