envreplace

Searches through files and replaces references to environment variables with the value of the named environment variable.

I use this to replace environment variables in config files at Docker container startup.

Example

Given a file test.file:

My File with an ${env.ENV_VAR}

And a variable set in the shell:

export ENV_VAR='environment variable'

You could run:

envreplace test.file

And test.file would be changed to:

My File with an environment variable

npm install -g envreplace

Supports specifying your own format for the regular expression that finds env var matches
Allows use of node.js file globbing
Verbose mode that logs all replacements
Option to fail on missing variables

envreplace --help