How do I set an environment variable in Makefile for Windows?

Question

I have the following Makefile:

PYTHON = python
.DEFAULT_GOAL = help
help:
    @echo ------------------------------Makefile for Flask app------------------------------
    @echo USAGE:
    @echo   make dependencies           Install all project dependencies
    @echo       make docker             Run Docker
    @echo       make env                Set environment variables
    @echo       make run                Run Flask app
    @echo       make test               Run tests for app
    @echo ----------------------------------------------------------------------------------
dependencies:
    @pip install -r requirements.txt
    @pip install -r dev-requirements.txt
docker:
    docker compose up

env:
    @set CS_HOST_PORT=5000
    @set CS_HOST_IP=127.0.0.1
    @set DATABASE_URL=postgresql://lv-python-mc:575@127.0.0.1:5482/Realty_DB
    @set REDIS_IP=127.0.0.1
    @set REDIS_PORT=6379
run:
    ${PYTHON} app.py    test:
    @${PYTHON} -m pytest

The set command doesn't work and the environment variables aren't set, what may be the problem?

Answer 1

You can certainly set environment variables that will be in effect for programs make will invoke . But make cannot set environment variables for shells that invoke make . So if your makefile runs a program then you can set an environment variable in your makefile that will be visible in that program.

This has nothing to do with make, by the way. This is a limitation (or feature, depending on your perspective) of the operating system. Try this experiment:

• Open a terminal.
• Run set FOO=bar
• Run echo %FOO% . See that it prints bar .
• From that same terminal start a new shell by running cmd.exe
• Now here run set FOO=nobar
• Run echo %FOO% . See that it prints nobar .
• Now exit the new shell by running exit
• Now run echo %FOO%

You'll see that instead of nobar , it still prints bar . That's because the OS does not allow a child program to modify the environment of its parent program.

So, there's nothing make can do about this.