Nix Flakes Modern Nix project management with hermeticity and reproducibility through flake.lock. Core Commands Project Management
Initialize a new flake in the current directory
nix flake init
Create a new flake from template
nix flake new hello -t templates
hello
Update flake.lock (updates all inputs)
nix flake update
Update specific input only
nix flake update nixpkgs
Lock without updating (create missing entries)
nix flake lock
Check flake for syntax and common errors
nix flake check
Show flake outputs
nix flake show
Show flake metadata (inputs, revisions)
nix flake metadata path:. nix flake info path:.
Alias for metadata
Prefetch flake and inputs into store
nix flake prefetch github:NixOS/nixpkgs nix flake prefetch-inputs path:.
Clone flake repository
nix flake clone nixpkgs --dest ./nixpkgs Running and Building Always prefix local flake paths with path: (e.g., path:. ) to ensure Nix uses all files in the directory without requiring them to be staged in Git.
Build the default package
nix build path:.
Build a specific output
nix build path:.
packageName
Run the default app
nix run path:.
Run a specific app from a flake
nix run path:.
appName
Run an app from a remote flake
nix run github:numtide/treefmt Development Environments In a headless environment, use nix develop with --command to run tasks within the environment.
Run a command inside the devShell
nix develop path:. --command make build
Check if current environment matches devShell
- nix develop path:.
- --command
- env
- Flake Structure (
- flake.nix
- )
- A basic
- flake.nix
- pattern:
- {
- description
- =
- "A basic flake"
- ;
- inputs
- =
- {
- nixpkgs
- .
- url
- =
- "github:nixos/nixpkgs/nixos-unstable"
- ;
- }
- ;
- outputs
- =
- {
- self
- ,
- nixpkgs
- }
- :
- let
- system
- =
- "x86_64-linux"
- ;
- pkgs
- =
- nixpkgs
- .
- legacyPackages
- .
- $
- {
- system
- }
- ;
- in
- {
- packages
- .
- $
- {
- system
- }
- .
- default
- =
- pkgs
- .
- hello
- ;
- devShells
- .
- $
- {
- system
- }
- .
- default
- =
- pkgs
- .
- mkShell
- {
- buildInputs
- =
- [
- pkgs
- .
- git pkgs
- .
- vim
- ]
- ;
- }
- ;
- }
- ;
- }
- Best Practices
- Locking
-
- Manage the
- flake.lock
- file to ensure reproducibility.
- Purity
-
- Flakes are "pure" by default. They cannot access files outside the flake directory unless they are tracked (e.g. in the git tree if using git).
- Non-Interactive
- When using nix develop , always use the --command flag to ensure scripts remain non-interactive. Debugging Flakes
Inspect inputs
nix flake metadata path:.
Evaluate a specific output
nix eval path:.