chattr

Additional Notes

chattr changes Linux extended file attributes such as immutable or append-only flags. These attributes are separate from normal Unix permissions.

Use it carefully for protecting important files, controlling append-only logs, or inspecting filesystem behavior.

Syntax

chattr [operator][attributes] file...

Parameters

• operator: + to add, - to remove, or = to set exactly.
• attributes: Attribute letters such as i or a.
• file: File or directory to change.

Common Attributes

• i: Immutable. File cannot be modified, removed, renamed, or linked by normal means.
• a: Append-only. File can only be opened for appending.
• A: Do not update access time.
• d: Exclude from dump backups.

Examples

sudo chattr +i important.conf

Make a file immutable.

sudo chattr -i important.conf

Remove the immutable attribute.

sudo chattr +a audit.log

Make a file append-only.

lsattr important.conf

View extended attributes.

Practical Notes

• Root may be needed to change many attributes.
• Immutable files can confuse package managers and editors.
• Attribute support depends on filesystem type.