Wednesday, 20 May 2015

Fields of an inode

Inode is a data structure used to represent a filesystem object, which can be one of various things including a file or a directory. Each inode stores the attributes and disk block location(s) of the filesystem object's data. Filesystem object attributes may include manipulation metadata (e.g. change, access, modify time), as well as owner and permission data (e.g. group-id, user-id, permissions).

ls -il
total 52
185033 -rw-------. 1 root root   979 Apr 25 23:23 anaconda-ks.cfg
393286 drwxr-xr-x. 2 root root  4096 Apr 29 09:09 Desktop
393290 drwxr-xr-x. 2 root root  4096 Apr 29 09:09 Documents
393287 drwxr-xr-x. 2 root root  4096 Apr 29 09:09 Downloads
393291 drwxr-xr-x. 2 root root  4096 Apr 29 09:09 Music
393292 drwxr-xr-x. 2 root root  4096 Apr 29 09:09 Pictures
185050 -rw-r--r--. 1 root root 11955 Apr 23  2013 post-install
185053 -rw-r--r--. 1 root root   552 Apr 23  2013 post-install.log
393289 drwxr-xr-x. 2 root root  4096 Apr 29 09:09 Public
393288 drwxr-xr-x. 2 root root  4096 Apr 29 09:09 Templates
393293 drwxr-xr-x. 2 root root  4096 Apr 29 09:09 Videos

File attributes in particular,

The size of the file in Kilo bytes

Device ID

User ID of the file

Group ID of the file

The file mode that determines the file type and how the owner, group, and others (world) can access the file
Additional system and user flags to further protect the file (note: this can be used limit the files use and modification)

Timestamps telling when the inode itself was last change (ctime, changing time), the file content was last modified (mtime or modification time), and when the file was last accessed (atime or access time)

A link counter that lists how many hard links point to the inode
Pointers to the disk blocks that store the file’s contents (more on that later)

Ref:-
http://en.wikipedia.org/wiki/Inode
http://www.linux-mag.com/id/8658/
http://teaching.idallen.com/dat2330/04f/notes/links_and_inodes.html

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