What are macOS extended attributes?
In macOS, Extended Attributes are metadata associated with files and directories that store additional information beyond standard file attributes like name, size, and timestamps. Extended attributes allow you to attach custom data to a file that can be used by applications, the operating system, or even the user. Each extended attribute consists of a name and value pair, which can contain any kind of data, such as text, binary data, or encoded settings.
Common use cases for extended attributes
- File Management: Add tags or metadata to organize files in ways beyond conventional folder structures.
- Security: For example, 'the com.apple.quarantine' flag is an extended attribute in macOS that marks files from untrusted sources (e.g., internet, email) as quarantined. This security measure protects users by requiring explicit approval before opening potentially harmful files.
- Application-specific data: Applications can add unique extended attributes for storing data that they need to function, which may be read back upon relaunching the app.
Does LucidLink support extended attributes?
Yes, LucidLink supports extended attributes, but there are possible limitations, which you can read more about in the section below.
While the vast majority of common attributes and workflows will work without issue, there are a few specific scenarios to consider.
Known limitations
LucidLink is actively working on improvements to mitigate these size limitations and enhance support for extended attributes in future updates. This will ensure smoother workflows, especially for users dealing with large or legacy files that require extensive metadata storage.
Below are some key limitations when working with extended attributes in LucidLink on macOS. These limitations primarily affect workflows involving unexpectedly large or legacy attributes.
Supported size of Extended Attributes
- On macOS Monterey and macOS Ventura, LucidLink supports reading extended attributes up to 512KB in size.
- On macOS Sonoma, the supported size increases to 4MB.
- There is no limit on macOS Sequoia
These size limitations primarily affect workflows that rely on ResourceForks, which can store larger data. ResourceForks are used in legacy macOS files but are now less common in modern applications, which typically store such resources in separate files or within application bundles. However, some older applications and legacy files may still use them.
Copying files with Extended Attributes larger than 1MB on macOS Sequoia
If you use the 'cp' command to copy files containing extended attributes larger than 1MB on Sequoia, the destination file may lose these large attributes. For better compatibility and preservation of extended attributes, we recommend using Finder or rsync, both of which successfully handle large extended attributes without issue.