cachix/devenv
Fast, Declarative, Reproducible, and Composable Developer Environments using Nix
{ "createdAt": "2022-10-22T20:10:10Z", "defaultBranch": "main", "description": "Fast, Declarative, Reproducible, and Composable Developer Environments using Nix", "fullName": "cachix/devenv", "homepage": "https://devenv.sh", "language": "Rust", "name": "devenv", "pushedAt": "2025-11-26T00:07:25Z", "stargazersCount": 5964, "topics": [ "developer-tools", "devenv", "nix" ], "updatedAt": "2025-11-26T00:07:29Z", "url": "https://github.com/cachix/devenv"}
devenv.sh - Fast, Declarative, Reproducible, and Composable Developer Environments
Section titled “devenv.sh - Fast, Declarative, Reproducible, and Composable Developer Environments”
Running devenv init generates devenv.nix:
{ pkgs, lib, config, inputs, ... }:
{ # https://devenv.sh/basics/ env.GREET = "devenv";
# https://devenv.sh/packages/ packages = [ pkgs.git ];
# https://devenv.sh/languages/ # languages.rust.enable = true;
# https://devenv.sh/processes/ # processes.dev.exec = "${lib.getExe pkgs.watchexec} -n -- ls -la";
# https://devenv.sh/services/ # services.postgres.enable = true;
# https://devenv.sh/scripts/ scripts.hello.exec = '' echo hello from $GREET '';
# https://devenv.sh/basics/ enterShell = '' hello # Run scripts directly git --version # Use packages '';
# https://devenv.sh/tasks/ # tasks = { # "myproj:setup".exec = "mytool build"; # "devenv:enterShell".after = [ "myproj:setup" ]; # };
# https://devenv.sh/tests/ enterTest = '' echo "Running tests" git --version | grep --color=auto "${pkgs.git.version}" '';
# https://devenv.sh/outputs/ # outputs = { # rust-app = config.languages.rust.import ./rust-app {}; # python-app = config.languages.python.import ./python-app {}; # };
# https://devenv.sh/git-hooks/ # git-hooks.hooks.shellcheck.enable = true;
# See full reference at https://devenv.sh/reference/options/}And devenv shell activates the environment.
Commands
Section titled “Commands”$ devenvhttps://devenv.sh 1.9.0: Fast, Declarative, Reproducible, and Composable Developer Environments
Usage: devenv [OPTIONS] [COMMAND]
Commands: init Scaffold devenv.yaml, devenv.nix, .gitignore and .envrc. generate Generate devenv.yaml and devenv.nix using AI shell Activate the developer environment. https://devenv.sh/basics/ update Update devenv.lock from devenv.yaml inputs. http://devenv.sh/inputs/ search Search for packages and options in nixpkgs. https://devenv.sh/packages/#searching-for-a-file info Print information about this developer environment. up Start processes in the foreground. https://devenv.sh/processes/ processes Start or stop processes. https://devenv.sh/processes/ tasks Run tasks. https://devenv.sh/tasks/ test Run tests. http://devenv.sh/tests/ container Build, copy, or run a container. https://devenv.sh/containers/ inputs Add an input to devenv.yaml. https://devenv.sh/inputs/ repl Launch an interactive environment for inspecting the devenv configuration. gc Delete previous shell generations. See https://devenv.sh/garbage-collection build Build any attribute in devenv.nix. direnvrc Print a direnvrc that adds devenv support to direnv. See https://devenv.sh/automatic-shell-activation. version Print the version of devenv. mcp Launch Model Context Protocol server for AI assistants help Print this message or the help of the given subcommand(s)
Options: -V, --version Print version information and exit
-v, --verbose Enable additional debug logs.
-q, --quiet Silence all logs
--log-format <LOG_FORMAT> Configure the output format of the logs.
[default: cli]
Possible values: - cli: The default human-readable log format used in the CLI - tracing-full: A verbose structured log format used for debugging - tracing-pretty: A pretty human-readable log format used for debugging
-j, --max-jobs <MAX_JOBS> Maximum number of Nix builds at any time.
[default: 8]
-u, --cores <CORES> Maximum number CPU cores being used by a single build.
[default: 2]
-s, --system <SYSTEM> [default: x86_64-linux]
-i, --impure Relax the hermeticity of the environment.
--no-eval-cache Disable caching of Nix evaluation results.
--refresh-eval-cache Force a refresh of the Nix evaluation cache.
--offline Disable substituters and consider all previously downloaded files up-to-date.
-c, --clean [<CLEAN>...] Ignore existing environment variables when entering the shell. Pass a list of comma-separated environment variables to let through.
--nix-debugger Enter the Nix debugger on failure.
-n, --nix-option <NAME> <VALUE> Pass additional options to nix commands.
These options are passed directly to Nix using the --option flag. See `man nix.conf` for the full list of available options.
Examples: --nix-option sandbox false --nix-option keep-outputs true --nix-option system x86_64-darwin
-o, --override-input <NAME> <URI> Override inputs in devenv.yaml.
Examples: --override-input nixpkgs github:NixOS/nixpkgs/nixos-unstable --override-input nixpkgs path:/path/to/local/nixpkgs
-O, --option <OPTION> <VALUE> Override configuration options with typed values.
OPTION must include a type: <attribute>:<type> Supported types: string, int, float, bool, path, pkg, pkgs
Examples: --option languages.rust.channel:string beta --option services.postgres.enable:bool true --option languages.python.version:string 3.10 --option packages:pkgs "ncdu git"
-P, --profile <PROFILE> Activate one or more profiles defined in devenv.nix.
Profiles allow you to define different configurations that can be merged with your base configuration.
See https://devenv.sh/profiles for more information.
Examples: --profile python-3.14 --profile backend --profile fast-startup
-h, --help Print help (see a summary with '-h')