You're about to be very surprised! echo old > a ln a b echo new > a cat a b # prints "new" and "new" Some programs like GNU sed [1

You're about to be very surprised! echo old > a ln a b echo new > a cat a b # prints "new" and "new" Some programs like GNU sed [1] do create new inodes, but that is a property of the application, not the filesystem: echo old > a ln a b sed -i 'c new' a cat a b # prints "new" and "old" With reflinks in a CoW filesystem the inodes are different from the start, but share the same underlying blocks: echo old > a cp --reflink=always a b ls -i a b # prints different inodes echo new > a cat a b # prints "new" and "old" [1] https://www.gnu.org/software/sed/manual/html_node/Command_002dLine-Options.html#index-_002di https://www.gnu.org/software/sed/manual/html_node/Command_00...