Add Set And Show Heroku Env Variables as a Heroku til

Author: jbranchaud

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
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 - [Upgrading From An Older Version On Mac](go/upgrading-from-an-older-version-on-mac.md)
 
+### Heroku
+
+- [Set And Show Heroku Env Variables](heroku/set-and-show-heroku-env-variables.md)
+
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heroku/set-and-show-heroku-env-variables.md

@@ -0,0 +1,30 @@
+# Set And Show Heroku Env Variables
+
+The `heroku` CLI includes the `config` command which will show all the env
+variables for the current app.
+
+```bash
+$ heroku config
+=== my-app Config Vars
+
+```
+
+At this point I have none set.
+
+I can set one with the `config:set` command and a key-value parameter.
+
+```bash
+$ heroku config:set PUBLIC_NEXT_URL=http://localhost:1235
+Setting PUBLIC_NEXT_URL and restarting ⬢ my-app... done, v3
+PUBLIC_NEXT_URL: http://localhost:1235
+```
+
+I can see the value that this specific variable is set to by calling it with
+`config:get`.
+
+```bash
+$ heroku config:get PUBLIC_NEXT_URL
+http://localhost:1235
+```
+
+[source](https://devcenter.heroku.com/articles/config-vars#using-the-heroku-cli)