A short note on inode number – Linux
What is inode number in Unix / Linux?
It’s simply a reference (idex) about the file and directory on the System. This is an entry in Inode table. This data structure uses to represent a file system object, this can be one of the various things such as file or directory. It’s a unique number for files and directories under a disk partition.
The file system attributes include metadata like access time, modification time etc; as well as ownership and permission details of files and directories.
Sample image 1
What are the important attributes included in inode?
The below mentioned keys are the different attributes in Unix file system and are included in inode.
- File type.
- File permission.
- Ownership and group.
- File size.
- File access, change and modification time.
- File deletion time.
- Number of links.
How do I check the inode details of a file or directory?
Do you have a shell access to your server? If so, yes! you can simply check the inode number by using the following commands:
- ls -i
See the sample outputs
1. By using ls command.
The switch “i” uses with ls command to find out the inode number of a file or directory. See the sample output pasted below:
[email protected]:~$ touch inode.check [email protected]:~$ ls -i inode.check 1179765 inode.check
Here the inode for the file “inode.check” is 1179765.
2. By using stat command.
The “stat” command will display the inode number along with a lot of other attributes. See the output:
[email protected]:~$ stat inode.check File: 'inode.check' Size: 0 Blocks: 0 IO Block: 4096 regular empty file Device: 806h/2054d Inode: 1179765 Links: 1 Access: (0664/-rw-rw-r--) Uid: ( 1000/ arunlal) Gid: ( 1000/ arunlal) Access: 2016-11-15 20:00:07.548968280 +0530 Modify: 2016-11-15 20:00:07.548968280 +0530 Change: 2016-11-15 20:00:07.548968280 +0530 Birth: -
In this output you can see a lot of attributes of the file “inode.check.”
You can also use these commands to check the details of directories. See one example pasted below:
[email protected]:~$ mkdir inode.check.dir [email protected]:~$ stat inode.check.dir File: 'inode.check.dir' Size: 4096 Blocks: 8 IO Block: 4096 directory Device: 806h/2054d Inode: 1314947 Links: 2 Access: (0775/drwxrwxr-x) Uid: ( 1000/ arunlal) Gid: ( 1000/ arunlal) Access: 2016-11-15 20:09:21.734325138 +0530 Modify: 2016-11-15 20:09:21.734325138 +0530 Change: 2016-11-15 20:09:21.734325138 +0530 Birth: -
Total inode usage on the Linux machine can be calculated from the ”df” command along with the usage of switch “i.” Please see the details pasted below:
$ df -i Filesystem Inodes IUsed IFree IUse% Mounted on udev 489347 557 488790 1% /dev tmpfs 494198 802 493396 1% /run /dev/sda6 3932160 238966 3693194 7% / tmpfs 494198 150 494048 1% /dev/shm
That’s it! Try it and add comments if you have any other ideas on it.