nix-build build a Nix expression nix-build --add-drv-link --no-link paths The nix-build command builds the derivations described by the Nix expressions in paths. If the build succeeds, it places a symlink to the result in the current directory. The symlink is called result. If there are multiple Nix expressions, or the Nix expressions evaluate to multiple derivations, multiple sequentially numbered symlinks are created (result, result-2, and so on). nix-build is essentially a wrapper around nix-instantiate (to translate a high-level Nix expression to a low-level store derivation) and nix-store --realise (to build the store derivation). The result of the build is automatically registered as a root of the Nix garbage collector. This root disappears automatically when the result symlink is deleted or renamed. So don’t rename the symlink. --add-drv-link Add a symlink in the current directory to the store derivation produced by nix-instantiate. The symlink is called derivation (which is numbered in the case of multiple derivations). The derivation is a root of the garbage collector until the symlink is deleted or renamed. --no-link Do not create a symlink to the output path. Note that as a result the output does not become a root of the garbage collector, and so might be deleted by nix-store --gc.