stat命令

功能说明：显示inode内容。
语　　法：stat [文件或目录]
补充说明：stat以文字的格式来显示inode的内容。

ls 命令及其许多参数提供了一些非常有用的文件信息。另一个不太为人所熟知的命令 stat 提供了一些更为有用的信息。 

下面演示了如何对可执行文件“oracle”（位于 $ORACLE_HOME/bin 目录下）使用此命令。  
 
# cd $ORACLE_HOME/bin   
# stat oracle   
  File: `oracle'   
  Size: 93300148        Blocks:182424     IO Block:4096   Regular File   
Device: 343h/835d       Inode: 12009652    Links: 1       
Access: (6751/-rwsr-s--x)  Uid:(  500/  oracle)   Gid:(  500/     dba)   
Access: 2006-08-04 04:30:52.000000000 -0400  
Modify: 2005-11-02 11:49:47.000000000 -0500  
Change: 2005-11-02 11:55:24.000000000 -0500  
注意使用该命令获得的信息：除了通常的文件大小（也可以使用 ls -l 命令获得）以外，您还获得了该文件占用的块数。通常的 Linux 块大小为 512 字节，因此一个大小为 93,300,148 字节的文件将占用 (93300148/512=) 182226.85 个块。由于块都是完整占用，因此该文件使用了一些整数个数的块。无需猜测就可以获得确切的块数。 

您还可以从以上输出中获得文件所有权的 GID 和 UID，以及权限的八进制表示形式 (6751)。如果要将文件恢复到它现在具有的相同权限，可以使用 chmod 6751 oracle，而不是显式拼写这些权限。 

以上输出最有用的部分是文件访问时间戳信息。该输出显示，该文件被访问的时间是 2006-08-04 04:30:52（显示在“Access:”的旁边），即 2006 年 8 月 4 日上午 4:30:52。这是某个人开始使用数据库的时间。该文件的date.html' target='_blank'>修改时间是 2005-11-02 11:49:47（显示在“Modify:”的旁边）。最后，“Change:”旁边的时间戳显示文件状态更改的时间。 

stat 命令的修改符 -f 显示了有关文件系统（而非文件）的信息： 
 
# stat -f oracle   
  File: "oracle"  
    ID: 0        Namelen:255     Type:ext2/ext3   
Blocks: Total: 24033242   Free: 15419301   Available: 14198462   Size: 4096  
Inodes: Total: 12222464   Free: 12093976     
  
另一个选项 -t 显示了完全相同的信息，只不过是在一行中显示的：    
  
# stat -t oracle    
oracle 93300148 182424 8de9 500 500 343 12009652 1 0 0 1154682061    
1130950187 1130950524 4096  

Everything in Unix is treated as files. This includes devices, directories and sockets — all of these are files. Stat command displays file or filesystem status as explained in this article.

File Stat – Display Information About File

For example, to find out more information about 101hacks.txt file, execute the stat command as shown below.

$ stat 101hacks.txt  File: `/home/sathiyamoorthy/101hacks.txt'  Size: 854       Blocks: 8          IO Block: 4096   regular fileDevice: 801h/2049dInode: 1058122     Links: 1Access: (0600/-rw-------)  Uid: ( 1000/ sathiya)   Gid: ( 1000/ sathiya)Access: 2009-06-28 19:29:57.000000000 +0530Modify: 2009-06-28 19:29:57.000000000 +0530Change: 2009-06-28 19:29:57.000000000 +0530

Details of Linux Stat Command Output

• File: `/home/sathiyamoorthy/101hacks.txt’ – Absolute path name of the file.
• Size: 854 – File size in bytes.
• Blocks: 8 – Total number of blocks used by this file.
• IO Block: 4096 – IO block size for this file.
• regular file – Indicates the file type. This indicates that this is a regular file. Following are available file types.
  • regular file. ( ex: all normal files ).
  • directory. ( ex: directories ).
  • socket. ( ex: sockets ).
  • symbolic link. ( ex: symbolic links. )
  • block special file ( ex: hard disk ).
  • character special file. ( ex: terminal device file ).
• Device: 801h/2049d  – Device number in hex and device number in decimal
• Inode: 1058122 – Inode number is a unique number for each file which is used for the internal maintenance by the file system.
• Links: 1 – Number of links to the file
• Access: (0600/-rw——-): Access specifier displayed in both octal and character format. Let us see explanation about both the format.
• Uid: ( 1000/ sathiya) – File owner’s user id and user name are displayed.
• Gid: ( 1000/ sathiya) – File owner’s group id and group name are displayed.
• Access: 2009-06-28 19:29:57.000000000 +0530 – Last access time of the file.
• Modify: 2009-06-28 19:29:57.000000000 +0530 – Last modification time of the file.
• Change: 2009-06-28 19:29:57.000000000 +0530 – Last change time of the inode data of that file.

Dir Stat – Display Information About Directory

You can use the same command to display the information about a directory as shown below.

$ stat /home/rameshFile: `/home/ramesh'Size: 4096 Blocks: 8 IO Block: 4096 directoryDevice: 803h/2051d Inode: 5521409 Links: 7Access: (0755/drwxr-xr-x) Uid: ( 401/ramesh) Gid: ( 401/ramesh)Access: 2009-01-01 12:17:42.000000000 -0800Modify: 2009-01-01 12:07:33.000000000 -0800Change: 2009-01-09 12:07:33.000000000 -0800

Details of File Permission:

File Permission In Octal Format

This information about the file is displayed in the Access field when you execute stat command. Following are the values for read, write and execute permission in Unix.

在学习到stat命令时，知道device部分显示的是设备的主编号和次编号，但是今天发现，如果查看设备文件的时候，显示编号是5h/5d。

这个是更加底层的设备，信息在这里：

/proc/self/mountinfo

里面有/dev目录的编号，第三列：0:5，就是这里。