chattr is the command in Linux that allows a user to set certain attributes of a file.
The similar-sounding commands chatr (from HP-UX) and lsattr (from AIX) exist but have unrelated functions.
However, the functionality has since been extended, fully or partially, to many other systems, including XFS, ReiserFS, JFS and OCFS2.
The btrfs file system includes the attribute functionality, including the C flag, which turns off the built-in copy-on-write (CoW) feature of btrfs due to slower performance associated with CoW.
UFS on BSD systems, and APFS, HFS+, SMB, AFP, and FAT on macOS support at least some flags.