What type of file does the immutable bit set prevent from being modified in Linux?

The immutable bit, when set on a file in Linux, prevents any modification to that file, regardless of its type. This includes preventing all operations typically associated with changing the content of the file, such as writing to or deleting it. By leveraging the immutable attribute, administrators can ensure that critical files remain unchanged and are protected from accidental modifications or deliberate tampering.

The immutable bit can be applied to any file type—regular files, directories, symbolic links, executables, and configuration files—making it a versatile feature for protecting important data across the filesystem. This broad applicability is why the correct understanding is that it affects all file types. Users can set the immutable bit using the command chattr +i filename, and once applied, even the root user will be inhibited from modifying the file until the immutable attribute is removed.

The other choices are specific classes of files and do not encompass the complete range of file types that the immutable bit protects, which is why they do not fully capture the functionality of this feature.