Linux chattr command

chattr (Change Attribute) is a command line Linux utility that is used to set/unset certain attributes to a file in Linux system to secure accidental deletion or modification of important files and folders, even though you are logged in as a root user.

chattr parameter and usage

Parameter	Usage
+a (Append Only)	Set the “append-only” attribute. Files with this attribute can only be opened in “append” mode for writing.
+i (Immutable)	Set the “immutable” attribute. Files with this attribute cannot be modified, deleted, or renamed, even by the root user.
+c (No-Copy On Write)	Disable the copy-on-write feature for files in a btrfs file system.
+u (Undeletable)	Mark the file as undeletable. Once set, the file cannot be deleted until this attribute is removed.
+s (Secure Deletion)	Enable secure deletion of a file. When a file with this attribute is deleted, its data blocks are overwritten with zeros.
+S (sync)	When a file with the ‘S’ attribute set is modified, the changes are written synchronously to the disk; this is equivalent to the ‘sync’ mount option applied to a subset of the files.
+A (atime)	its time record is not modified. This avoids a certain amount of disk I/O for laptop systems.
+u	its contents are saved. This allows the user to ask for its undeletion.

’-‘ every parameter means remove attribute. and it can be displayed by ‘lsattr’