nix3-flake

nix flake subcommand [options]

nix3-flake is the manual page for nix flake, the command for creating, modifying and querying flakes. A flake is a source tree (usually a Git repository) with a flake.nix at its root declaring its inputs (dependencies) and outputs (packages, dev shells, NixOS configurations and so on). Input versions are pinned in flake.lock.Flakes are referenced with flakerefs such as nixpkgs, github:NixOS/nixpkgs/nixos-unstable, git+https://example.org/repo or a path like .; an output is selected with #, e.g. .#default.

show [flake]

Show the outputs provided by a flake. --all-systems includes every system, --json gives machine-readable output.

Update the lock file, all inputs by default. --flake url selects another flake than the current directory.

Create missing lock file entries without updating existing ones.

Create a flake in the current (or given) directory from a template (-t).

Check whether the flake evaluates and run its tests. --all-systems checks every system.

Show flake metadata such as the locked revision and input tree.

Copy a flake and all its inputs to a store.

Clone a flake's repository.

Download a flake source tree, or the inputs of a flake, into the Nix store.

Display help information.

There is no nix3 executable: the new-CLI man pages are named nix3-subcommand (man nix3-flake, man nix3-flake-update). Run the commands as nix flake.Requires the nix-command and flakes experimental features. In a Git repository only files tracked by Git are visible to the flake, so git add new files first. nix flake update used to update the flake given as argument; it now takes input names and uses --flake to select the flake.

Flakes and nix flake were introduced as an experimental feature in Nix 2.4 (2021). nix flake info is an older alias of nix flake metadata. Nix 2.19 (2023) changed nix flake update to accept input names, replacing nix flake lock --update-input.

nix(1), nix-flake(1), nix3-build(1), nix-flake-show(1), nix-flake-init(1), nix-registry(1)

Source code · Documentation