Cheatsheet: Difference between revisions
→Inode Number
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== Inode Number ==
Source: [https://linoxide.com/linux-command/linux-inode/ linoxide.com]
* Inode is entry in inode table containing metadata about a regular file and directory.
* An inode is a data structure on a traditional Unix-style file system such as ext3 or ext4.
* Linux extended filesystems such as ext2 or ext3 maintain an array of these inodes: the inode table.
* This table contains list of all files in that filesystem.
* The individual inodes in inode table have a unique number (unique to that filesystem) - the inode number.
* There are some data about files, such as their size, ownership, permissions, timestamp etc.
* This meta-data about a file is managed with a data structure known as an inode (index node).
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* Move or Rename a file: if destination is same filesystem as the source, Has no impact on inode number, it only changes the time stamps in inode table.
* Delete a file: Deleting a file in Linux decrements the link count and freeing the inode number to be reused.
* A Directory cannot hold two files with same name because it cannot map one name with two different inode numbers.
* The inode number of / directory is fixed, and is always 2.
*Inode number (or index number) consists following attributes:
File
Permissions:
Link count: The number of hard link relative to an inode
User ID: Owner of file
Group ID: Group owner
Size of file: or major/minor number in case of some special files
Time stamp: Access time, modification time and (inode) change time
Attributes: Immutable' for example
Access control list: Permissions for special users/groups
Other metadata about the file
*Check info:
df -i ==> Inodes on Filesystem
df -i /dev/vda1 ==> Inodes on Filesystem
ls -il myfile.txt ==> Show inode no of file
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stat unetbootin.bin ==> Show all details of file
stat --format=%i unetbootin.bin ==> Shows only inode no
* Manipulate the filesystem meta data
List the contents of the filesystem superblock
tune2fs -l /dev/sda6 | grep inode
Make sure files on the file system are not being accessed:
mount -o remount /yourfilesystem
debugfs /dev/sda1 ==> Manipulate FS here
You can use debugfs to undelete a file by using its inode and indicating a file
* Free Inodes on Filesystem
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