Advanced dotenv config files for bash scripts

A technique commonly used practice in (deployment of) software projects is to put your local configuration, environment variables and secrets in a .env file in the root of your project. This .env file is structured as a one-dimensional lookup table (a list of key=value lines), and saved only on that server, never checked in to the project code.

Every programming/scripting language has at least 1 popular package dedicated to exactly this:

There is, however, no such package for bash. The reason is that the .env syntax can be executed by bash as-is, no need to write a package for this1.

For bashew (my bash scripting micro-framework), I have created a more evolved .env strategy, with multiple .env files (potentially) read when a script executes. It looks for 4 separate .env files in a fixed sequence and, if they exist, they are executed:

import_env_if_any() {
    local env_files=("$script_install_folder/.env"
    local env_file
    for env_file in "${env_files[@]}"; do
        if [[ -f "$env_file" ]]; then
            debug "$config_icon Read config from [$env_file]"
            source "$env_file"

How does this work? Let’s take splashmark as an example.

  1. the $HOME/.basher/cellar/bin/splashmark/.env2 contains the Unsplash and Pixabay API keys that the script needs to search for/download images
  2. I have a symlink sm_github -> and the sm_github.env file contains all the settings specific for my GitHub images: width, height, font-size …
  3. for certain projects like Every country in the world in 1 (Unsplash) photo I can create a .env file in the project’s image folder and save the settings for those images.
  4. I could have separate .env files for separate symlinked aliases.

I have found having this flexibility in every script I create makes life really easier.

  1. Executing a .env file in bash has the advantage/danger that you can execute arbitrary code inside a .env file, which is great for things like YEAR_NOW=$(date '+%Y') 

  2. resolving the installation folder is explained in Find installation folder for bash scripts 

💬 devops 🏷 bashew 🏷 github 🏷 env 🏷 environment 🏷 bash