consub is a simple configuration substitution tool.
Download the binary from the release section or compile it. Then run:
consub .vars.env output.tpl.txt output.txt
The .vars.env file must be in the following format:
VAR=test
The output.tpl.txt file can then be configured like this:
My ${VAR} configuration!
The resulting output.txt file will look like this:
My test configuration!
MIT