Dotenv

<h1 align="center"> dotenv 🌴 </h1>

dotenv is a library that loads environment variables from a .env file into std.os.environ. Storing configuration in the environment separate from code is based on The Twelve-Factor App methodology.

This library is a Zig language port of nodejs dotenv.

Test with Zig 0.15.2

Quick Start

Automatically find the .env file and load the variables into the process environment with just one line.

const std = @import("std");
const dotenv = @import("dotenv");

pub fn main() !void {
    const allocator = std.heap.page_allocator;

    try dotenv.load(allocator, .{});
}

By default, it will search for a file named .env in the working directory and its parent directories recursively. Of course, you can specify a path if desired.

pub fn main() !void {
    try dotenv.loadFrom(allocator, "/app/.env", .{});
}

Since writing to std.os.environ requires a C setenv call, linking with C is necessary.

If you only want to read and parse the contents of the .env file, you can try the following.

pub fn main() !void {
    var envs = try dotenv.getDataFrom(allocator, ".env");

    var it = envs.iterator();
    while (it.next()) |*entry| {
        std.debug.print(
            "{s}={s}\n",
            .{ entry.key_ptr.*, entry.value_ptr.*.? },
        );
    }
}

This does not require linking with a C library. The caller owns the memory, so you need to free both the key and value in the hashmap.

.env Syntax

NAME_1="VALUE_1"
NAME_2='VALUE_2'
NAME_3=VALUE_3

Multiline values

The value of a variable can span multiple lines(quotes are required).

PRIVATE_KEY="-----BEGIN RSA PRIVATE KEY-----
ABCD...
-----END RSA PRIVATE KEY-----"

Comments

Comments start with a #.

# This is a comment
NAME="VALUE" # comment

Variable Expansion

You can reference a variable using ${}, and the variable should be defined earlier.

HO="/home"
ME="/koyori"

HOME="${HO}${ME}"  # equal to HOME=/home/koyori

LICENSE

MIT License Copyright (c) 2023-2025, Hanaasagi