Extended File Attributes (xattr)

The xattr command is a powerful utility in Linux and other Unix-like systems used to manage extended filesystem attributes. These attributes are key-value pairs that can be associated with files and directories, providing a way to store metadata beyond the standard file permissions and ownership. This is useful for various purposes, such as storing security information, access control lists, or application-specific data.

Understanding Extended Attributes

Extended attributes allow you to attach arbitrary metadata to files. Unlike traditional file metadata, extended attributes are not part of the file's content but are stored separately by the filesystem. The xattr command provides a user-friendly interface to interact with these attributes.

Common xattr Operations

Here are some of the most common operations you can perform with the xattr command:

Listing Extended Attributes

To view all extended attributes associated with a file, use the -l option:

# List key:value extended attributes for a given file:
xattr -l file

Writing Extended Attributes

You can set or update an extended attribute using the -w (write) option. This requires specifying the attribute key, the attribute value, and the target file:

# Write an attribute for a given file:
xattr -w attribute_key attribute_value file

Deleting Extended Attributes

To remove a specific extended attribute, use the -d (delete) option, providing the attribute key and the file:

# Delete an attribute from a given file:
xattr -d attribute_key file

Clearing All Extended Attributes

If you need to remove all extended attributes from a file at once, the -c (clear) option is useful:

# Delete all extended attributes from a given file:
xattr -c file

Recursive Deletion

For managing attributes within directories and their subdirectories, the -r (recursive) option combined with -d allows for bulk operations:

# Recursively delete an attribute in a given directory:
xattr -rd attribute_key directory

While xattr is the primary tool for interacting with extended attributes, other commands like setfattr and getfattr offer similar functionality, often with slightly different syntax or features. For deeper understanding of filesystem attributes and their implementation, consulting the Linux man pages for xattr, setfattr, and getfattr is highly recommended. You can also refer to documentation on specific filesystem types (e.g., ext4, XFS) for details on their extended attribute support.

Extended File Attributes (xattr) - Linux Command Line Utility