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