Overlooked Linux Mv Option Replaces Three Commands with One

GNU coreutils 9.5 introduced an `mv --exchange` option that swaps two existing paths in one operation, avoiding the traditional sequence of three moves and a temporary filename. That older method can briefly leave one name missing and may leave the swap incomplete if a command fails. On Linux, `--exchange` uses the kernel’s `renameat2()` system call with `RENAME_EXCHANGE`, making the name swap atomic: both paths remain present throughout. For example, exchanging `nginx.conf` and `nginx.conf.new` puts the new configuration in the first location while preserving the old one under the second name; running the command again reverses the change.

The option also works for directories, allowing whole directory trees - such as a live release and a newly deployed version - to trade names without moving their contents. When both arguments are existing directories, add `-T` so `mv` treats the second argument as a path to exchange rather than a destination directory. Both paths must be on the same filesystem, and that filesystem must support the operation; ext4, Btrfs, XFS, and tmpfs are listed as supported examples. Cross-filesystem exchanges fail because copying and deleting would not be atomic. Check availability with `mv --version` or `mv --help`; systems with GNU coreutils 9.5 or later, including recent NixOS, Fedora, and Debian 13 installations, may provide it.