Sharing env vars between commands

[letto4135]

@casey idk if this is cool enough to add to the readme, but it works if you really need to share env vars.

Define your env variables at the beginning of the file like you normally would. Any command that needs to set one of those variables can use sed to replace the first occurrence of it, then the next just command will pick up the new environment variables.

This allows me to run just start dev, just start local, or just start prod without having to change any env variables.

default: start
set export

ENV := "prod"
POSTGRES_DB := "postgres"
DEBUG := "False"
DISTRO := "mac"

start ENVIRONMENT='dev':
  just set-$ENVIRONMENT
  just run

run:
  echo "STARTING"
  docker compose up -d --build

set-mac env db debug:
  sed -Ei '' '1,/ENV :=.*$/ s/ENV :=.*$/ENV := "{{env}}"/g' Justfile
  sed -Ei '' '1,/POSTGRES_DB :=.*$/ s/POSTGRES_DB :=.*$/POSTGRES_DB := "{{db}}"/g' Justfile
  sed -Ei '' '1,/DEBUG :=.*$/ s/DEBUG :=.*$/DEBUG := "{{debug}}"/g' Justfile

set-linux env db debug:
  sed '0,/ENV :=.*$/{s/ENV :=.*$/ENV := "{{env}}"/}' Justfile
  sed '0,/POSTGRES_DB :=.*$/{s/POSTGRES_DB :=.*$/POSTGRES_DB := "{{db}}"/}' Justfile
  sed '0,/DEBUG :=.*$/{s/DEBUG :=.*$/DEBUG := "{{debug}}"/}' Justfile

set-local:
  just set-$DISTRO 'prod' 'local' 'False'

set-prod:
  just set-$DISTRO 'prod' 'postgres' 'False'

set-dev:
  just set-$DISTRO 'dev' 'postgres' 'True'