Variable and Environment Variable in GNU Make

README.md

$ cat Makefile
.PHONY: all

export AWS_PROFILE ?= acme
AWS_REGION ?= us-west-2

all:
        @echo AWS_PROFILE=$(origin AWS_PROFILE)
        @echo AWS_REGION=$(origin AWS_REGION)
        bash test.sh

$ cat test.sh
#!/bin/bash

echo AWS_PROFILE=$AWS_PROFILE
echo AWS_REGION=$AWS_REGION

$ make
AWS_PROFILE=file
AWS_REGION=file
bash test.sh
AWS_PROFILE=acme
AWS_REGION=

$ make AWS_PROFILE=hoge AWS_REGION=fuga
AWS_PROFILE=command line
AWS_REGION=command line
bash test.sh
AWS_PROFILE=hoge
AWS_REGION=fuga