# [devenv.sh](https://devenv.sh) - Fast, Declarative, Reproducible, and Composable Developer Environments
[](https://builtwithnix.org)
[](https://discord.gg/naMgvexb6q)
[](https://github.com/cachix/devenv/releases)
[](https://github.com/cachix/devenv/actions/workflows/buildtest.yml?branch=main)
Running ``devenv init`` generates ``devenv.nix``:
```nix
{ pkgs, ... }:
{
# https://devenv.sh/basics/
env.GREET = "devenv";
# https://devenv.sh/packages/
packages = [ pkgs.git ];
enterShell = ''
hello
'';
# https://devenv.sh/tests/
enterTest = ''
echo "Running tests"
git --version | grep --color=auto "${pkgs.git.version}"
'';
# https://devenv.sh/languages/
languages.nix.enable = true;
# https://devenv.sh/scripts/
scripts.hello.exec = "echo hello from $GREET";
# https://devenv.sh/services/
services.postgres.enable = true;
# https://devenv.sh/git-hooks/
git-hooks.hooks.shellcheck.enable = true;
# https://devenv.sh/processes/
processes.ping.exec = "ping localhost";
}
```
And ``devenv shell`` activates the environment.
## Commands
```
$ devenv
https://devenv.sh 1.6.0: 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.
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
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
Maximum number of Nix builds at any time.
[default: 8]
-u, --cores
Maximum number CPU cores being used by a single build.
[default: 2]
-s, --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 [...]
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
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
Override inputs in devenv.yaml.
Examples:
--override-input nixpkgs github:NixOS/nixpkgs/nixos-unstable
--override-input nixpkgs path:/path/to/local/nixpkgs
-O, --option
