What is true about the owner of a file?

The Linux VFS and underlying filesystems such as ext4 record a single UID and a single GID inside each file's inode. This is an immutable structural property of the permission model - a file cannot have multiple owning users or multiple owning groups simultaneously, and it cannot exist without both an owning user and an owning group.

Ownership and permission bits are independent metadata; a file owner's read, write, or execute bits can be removed with chmod, allowing a situation where the owner is denied access to their own file.

The owning user of a file is not required to be a member of the file's owning group; group membership and file group ownership are managed separately and can be completely unrelated.

Deleting a user removes their entry from /etc/passwd but leaves all their files intact on disk; those files will display the raw numeric UID rather than a username until ownership is reassigned.

The `chown` command allows root - and on some systems the current file owner - to transfer file ownership to a different user at any time after the file is created.