Suppose you want to write-protect some important files on Linux, so that they cannot be deleted or tampered with by accident or otherwise. In other cases, you may want to prevent certain configuration files from being overwritten automatically by software. While changing their ownership or permission bits on the files by using chown or chmod is one way to deal with this situation, this is not a perfect solution as it cannot prevent any action done with root privilege. That is when chattr comes in handy.

chattr is a Linux command which allows one to set or unset attributes on a file, which are separate from the standard (read, write, execute) file permission. A related command is lsattr which shows which attributes are set on a file. While file attributes managed by chattr and lsattr are originally supported by EXT file systems (EXT2/3/4) only, this feature is now available on many other native Linux file systems such as XFS, Btrfs, ReiserFS, etc.