dotenv - .env configuration files

Import with import "dotenv.j" as dotenv;. Read the KEY=VALUE files that keep configuration and secrets out of source. parse turns text into a map of string to string, read parses a file, and load parses a file and sets each variable in the process environment. Over fs + strings + os; pure .j, runs on both binaries.

import "dotenv.j" as dotenv;

def cfg as map of string to string init dotenv.parse("PORT=8080\n# note\nNAME=\"ada\"");
io.printf("%s\n", $cfg["PORT"]);     # 8080

dotenv.load(".env");                  # or set them in the environment

Runnable: examples/modules/dotenv_demo.j.

Functions

Syntax

Each non-blank, non-comment line is a KEY=VALUE assignment:

# a comment line
PORT=8080
export NAME="ada lovelace"     # a leading `export` is ignored
GREETING='hi # not a comment'  # single quotes are literal
PATH="/a\t/b"                  # double quotes expand \n \t \r
TOKEN=abc123        # trailing inline comment (unquoted values only)
EMPTY=

• Comments - a line starting with # is skipped; on an unquoted value a # (space then hash) starts an inline comment. Inside quotes, # is literal.
• export - a leading export prefix is stripped, so a file that doubles as a shell script parses the same.
• Double quotes expand the escapes \n, \t, \r (and \" for a literal quote); an unknown escape keeps its character.
• Single quotes are literal - no escapes, no interpolation.
• Unquoted values are trimmed of surrounding whitespace.
• The value may contain = (only the first = splits the line); a line with no = or an empty key is ignored; a later duplicate key wins.

Scope

• No variable interpolation. ${OTHER} inside a value is not expanded (the value is taken literally); reference other variables in your program instead.
• No multi-line values. Each assignment is one line.
• load overwrites. It sets every parsed variable with os.setEnv, replacing any existing value. To make .env a default (don’t override a real environment variable), read the map and set only the keys os.getEnv reports as empty.

See also

• fs.md - the file read read / load use.
• os.md - os.setEnv / os.getEnv for the environment.
• toml.md - for richer, typed, nested configuration.
• modules/index.md - the module catalog and import rules.