How to use the command xattr (with examples)

The xattr command is a utility used to work with extended filesystem attributes in macOS. Extended attributes are key:value pairs that can be associated with a file or directory. They provide a way to store metadata or additional information about files. The xattr command allows users to list, write, delete, or manipulate extended attributes for a given file or directory.

Use case 1: List key:value extended attributes for a given file

Code:

xattr -l file

Motivation:

This use case is helpful when you want to view the extended attributes associated with a specific file. By listing the attributes, you can see any additional metadata or information that might be stored along with the file.

Explanation:

• xattr: The command to work with extended filesystem attributes.
• -l: The option to list the extended attributes.
• file: The path of the file for which you want to list the extended attributes.

Example output:

com.apple.metadata:kMDItemWhereFroms:
00000000  62 70 6C 69 73 74 30 30 A1 ...                                             |bplist00.¦|
00000010  01 02 5F 10 69 6C 2E 61 70 70 6C 65 2E 73 61 66 |.._.il.apple.saf|
00000020  61 72 69 2D 6C 65 73 73 2D 70 6C 75 67 2D 69 6E |ari-less-plug-in|
00000030  66 6F 00 08 0F 78 2D 75 6E 69 71 75 65 2E 2D 73 |fo...x-unique.-s|
00000040  61 66 61 72 69 2D 6C 65 73 73 2D 63 6F 64 65 63 |afari-less-codec|
00000050  73 00 00 00 00 00 00 05 77 01 BB 15 C8 01 01 00 |s.......w.......|
...

Use case 2: Write an attribute for a given file

Code:

xattr -w attribute_key attribute_value file

Motivation:

This use case allows you to write an extended attribute with a specific attribute key and value to a file. It can be used to store additional metadata or information about the file.

Explanation:

• xattr: The command to work with extended filesystem attributes.
• -w: The option to write an extended attribute.
• attribute_key: The key of the extended attribute.
• attribute_value: The value of the extended attribute.
• file: The path of the file for which you want to write the extended attribute.

Example output:

No output is displayed if the write operation is successful.

Use case 3: Delete an attribute from a given file

Code:

xattr -d com.apple.quarantine file

Motivation:

This use case is useful when you want to remove a specific extended attribute from a file. In this example, we are deleting the com.apple.quarantine attribute, which is used by macOS to indicate that the file was downloaded from the internet and may be potentially harmful.

Explanation:

• xattr: The command to work with extended filesystem attributes.
• -d: The option to delete an extended attribute.
• com.apple.quarantine: The name of the attribute to be deleted.
• file: The path of the file from which the attribute should be deleted.

Example output:

No output is displayed if the delete operation is successful.

Use case 4: Delete all extended attributes from a given file

Code:

xattr -c file

Motivation:

This use case is helpful when you want to remove all extended attributes from a file. It can be useful in scenarios where you want to reset the file’s metadata or clear any additional information associated with the file.

Explanation:

• xattr: The command to work with extended filesystem attributes.
• -c: The option to delete all extended attributes.
• file: The path of the file from which all extended attributes should be deleted.

Example output:

No output is displayed if the delete operation is successful.

Use case 5: Recursively delete an attribute in a given directory

Code:

xattr -rd attribute_key directory

Motivation:

This use case allows you to recursively delete a specific extended attribute from all files and directories within a given directory. It can be useful when you want to remove a particular attribute from a directory hierarchy.

Explanation:

• xattr: The command to work with extended filesystem attributes.
• -r: The option to perform the operation recursively.
• -d: The option to delete an extended attribute.
• attribute_key: The key of the extended attribute to be deleted.
• directory: The path of the directory within which the attribute should be deleted.

Example output:

No output is displayed if the delete operation is successful.

Conclusion:

The xattr command is a powerful utility to work with extended filesystem attributes in macOS. With various options and use cases, it provides a way to manage extended attributes for files and directories. Whether you need to view, write, delete, or manipulate extended attributes, the xattr command can assist you in working with metadata or additional information associated with your files or directories.