path

$ nix-build -A path
/nix/store/x3zlw3d13gb4wxk3ykhh0hmd10sq4arb-system-path

While extra-utils provides a set of symlinks pointing to busybox to the stage-1 script, path provides a set of symlinks pointing to various executables in the Nix store to the stage-2 script.

path is defined in the system-path.nix module.