Metadata

In addition to the file type, ownership, access permissions, and reference count metadata, files can contain a wealth of other information that can be useful for various purposes. One such set of information is the creation, access, and modified timestamps, which are stored as metadata in the file system and are abbreviated as ctime, atime, and mtime respectively.

The ctime, or “change time,” represents the time when the file’s inode was last modified, such as when the file’s permissions were changed or the file was moved or renamed. The atime, or “access time,” indicates the last time the file was accessed, such as when it was opened or read. Finally, the mtime, or “modification time,” represents the time when the file’s content was last modified.

In addition to these standard timestamp fields, some file systems allow for additional metadata fields to be added to inodes or even allow for custom-defined metadata fields to be added for different file types. For example, a digital image file may have additional metadata fields such as the image resolution or color profile stored in its inode. Other types of files may have metadata fields such as author, description, or keywords.

These additional metadata fields can be useful for various purposes such as search indexing, file organization, and metadata-based filtering or sorting. They can also provide additional information about the file that may be useful for applications that interact with the file. However, it’s important to note that not all file systems support custom metadata fields and that different file systems may store metadata differently, so it’s important to understand the specific file system being used when working with non-standard metadata.