nv is a lightweight utility to load context specific environment variables from either a single or multiple .env files before executing a command or command line program, along with its parameters.

As of version 2, the environment is cleared-out before loading context specific variables, except for $PATH.

Warning

If you are using a version manager such as asdf, both variables $HOME and $USER could be required. Please see the Troubleshooting section for more information.

Why use nv when there are many other tools that do pretty much the same thing automatically?

The difference is that nv feeds an explicit environment to the process it starts, while those other tools fetch an environment (based on some filename convention) after the process is started.

nv is also not language-specific nor framework-specific — it just feeds some environment into the command it’s given to run.

nv is available via Homebrew and as a downloadable binary from the releases page.

nv is available as downloadable binaries from the releases page.

nv is available as a downloadable binary from the releases page.

Alternatively, you can build it from source.

1. Verify you have Go 1.16 installed

~> go version

If Go is not installed, follow the instructions on the Go website

2. Clone this repository

~> git clone https://github.com/jcouture/nv.git
~> cd nv

3. Build

~> go mod tidy
~> go build ./cmd/nv/

While the development version is a good way to take a peek at nv’s latest features before they get released, be aware that it may contains bugs. Officially released versions will generally be more stable.

Create a .env file as follows:

PORT=4200
SECRET_KEY_BASE=3b4476c0f6793b575050a1241438c32de8cbd3b7dec67910369657e1c4c41785
# Comments are supported
DATABASE_URL=postgres://dbuser:@localhost:5432/playground_dev?pool=10

You are then ready to use nv to load your context specific environment variables.

~> nv .env rails server -p 2808

It is possible to load multiple .env files by separating each filenames with a comma. If a variable exists in more than one file, its value will simply be overriden as parsing goes.

~> nv .env,.env.dev rails server -p 2808

You might need to have global environment variables, overriding context specific ones. Create a file named ~/.nv at the root of your home directory. It has the same format, and will be loaded last.

If after executing a command with nv, such as:

~> nv .env rails --version

you get the following error:

unknown command: rails. Perhaps you have to reshim?

add the following to your ~/.nv file:

HOME=<your home directory>
USER=<your username>

nv is released under the MIT license. See LICENSE for details.

The nv leaf logo is based on this icon by Nick Bluth, from the Noun Project. Used under a Creative Commons BY 3.0 license.