Inodes

Inodes

Information about each file is stored in a structure called an inode. The word inode is an abbreviation of the term index node. An inode is a data structure that stores all information about a file except its name, which is stored in the directory. Each inode has an identifying inode number, which is unique across the filesystem that includes the file.

An inode contains this information:

the type of the file (see the next section, "Types of Files," for more information)
the access mode of the file; the mode defines the access permissions read, write, and execute and may also contain security labels and access control lists
the number of hard links to the file (see the section "Hard Links and Symbolic Links" for more information)
who owns the file (the owner's user-ID number) and the group to which the file belongs (the group-ID number)
the size of the file in bytes
the date and time the file was last accessed, and last modified
information for finding the file's data within the disk partition or logical volume
the pathname of symbolic links (when they fit and on XFS filesystems only)

You can use the ls command with various options to display the information stored in inodes. For example, the command ls -l displays all but the last two items in the list above in the order listed (the date shown is the last modified time).

Inodes do not contain the name of the file or its directory.