Settings View Source Dotenv File Format

.env files (a.k.a. "dotenv") store key-value pairs in a format descended from simple bash files that exported environment variables.

This implementation cleaves closely to the format described by the original dotenv package, but it is not a direct match (by design).

Typically, a dotenv (.env) file is formatted into simple key-value pairs:

S3_BUCKET=YOURS3BUCKET
SECRET_KEY=YOURSECRETKEYGOESHERE

Optionally, you may add export in front of each line so you can source the file in Bash:

export S3_BUCKET=YOURS3BUCKET
export SECRET_KEY=YOURSECRETKEYGOESHERE

variable-names

Variable Names

For the sake of portability (and sanity), environment variable names must consist solely of letters, digits, and the underscore ( _ ) and must not begin with a digit. In regex-speak, the names must match the following pattern:

[a-zA-Z_]+[a-zA-Z0-9_]*

example-variable-names

Example variable names

DATABASE_URL  # ok  
foobar        # ok  
NO-WORK       # <-- invalid !!!
ÜBER          # <-- invalid !!!
2MUCH         # <-- invalid !!!

values

Values

Values are to the right of the equals sign. They may be quoted. Using single quotes will prevent variables from being interpolated.

SIMPLE=xyz123
INTERPOLATED="Multiple\nLines and variable substitution: ${SIMPLE}"
NON_INTERPOLATED='raw text without variable interpolation'
MULTILINE = """
long text here,
e.g. a private SSH key
"""

escape-sequences

Escape Sequences

The following character strings will be interpreted (i.e. escaped) as specific codepoints in the same way you would expect if the values were assigned inside a script. Remember: when a text file is read, it is read as a series of utf8 encoded code points. Character sequences like \n have no special meaning until they are "escaped" and a combination of codepoints is replaced by a single codepoint.

• \n Linefeed (aka newline); <<92, 110>> -> <<10>>
• \r Carriage return; <<92, 114>> -> <<13>>
• \t Tab; -> <<92, 116>> -> <<9>>
• \f Form feed; -> <<92, 102>> -> <<12>>
• \b Backspace; -> <<92, 98>> -> <<8>>
• \" Double-quote; -> <<92, 34>> -> <<34>>
• \' Single-quote; -> <<92, 39>> -> <<39>>
• \\ Backslash; -> <<92, 92>> -> <<92>>
• \uFFFF Unicode escape (4 hex characters to denote the codepoint)

If a backslash precedes any other character, that character will be interpreted literally: i.e. the backslash will be ignored and removed from output.

interpolation-a-k-a-variable-substitution

Interpolation (a.k.a. Variable Substitution)

Values left unquoted or wrapped in double-quotes will interpolate variables in the ${VAR} syntax. This can be useful for referencing existing system environment variables or to reference variables previously parsed.

For example:

USER=admin
EMAIL=${USER}@example.org
DATABASE_URL="postgres://${USER}@localhost/my_database"
CACHE_DIR=${PWD}/cache

Multi-line values (e.g. private keys) can use the triple-quoted heredoc syntax:

PRIVATE_KEY="""
-----BEGIN RSA PRIVATE KEY-----
...
HkVN9...
...
-----END DSA PRIVATE KEY-----
"""

non-interpolated

Non-Interpolated

If your values must retain ${} in their output, wrap the value in single quotes, e.g.:

PASSWORD='!@G0${k}k'
MESSAGE_TEMPLATE='''
    Hello ${PERSON},

    Nice to meet you!
'''

comments

Comments

The hash-tag # symbol denotes a comment when on its own line or when it follows a quoted value. It is not treated as a comment when it appears within quotes.

# This is a comment
SECRET_KEY=YOURSECRETKEYGOESHERE # also a comment
SECRET_HASH="something-with-a-hash-#-this-is-not-a-comment"