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.
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.
You can install nv as a Homebrew package on macOS:
~> brew install jcouture/nv/nv
Or you can build it from source:
~> mkdir nv
~> cd nv
~> set -x GOPATH $PWD
~> go get -u github.com/jcouture/nv
You 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 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.
nv is released under the MIT license. See LICENSE for details.