exchangedata(2) on macOS
The text 61a0ec6bad73, as macOS 26.3, macOS 26.2, macOS 26.1, macOS 26.0, macOS 15.6, macOS 15.5, macOS 15.4, macOS 15.3, macOS 15.2, macOS 15.1, macOS 15.0, macOS 14.6, macOS 14.5, macOS 14.4, macOS 14.3, macOS 14.2, macOS 14.1, macOS 14.0, macOS 13.5, macOS 13.4, macOS 13.3, macOS 13.2, macOS 13.1, macOS 13.0, macOS 12.5, macOS 12.4, macOS 12.3, macOS 12.2, macOS 12.1, macOS 12.0.1, macOS 11.5, macOS 11.4, macOS 11.3, macOS 11.2, macOS 11.1, macOS 11.0.1, macOS 10.15.6, macOS 10.15.5, macOS 10.15.4, macOS 10.15.3, macOS 10.15.2, macOS 10.15.1, macOS 10.15, macOS 10.14.6, macOS 10.14.3, macOS 10.14.2, macOS 10.14.1 shipped it.
atomically exchange data between two files