Add Read Existing Dot Env File Into Env Vars as a Mise TIL

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
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-_1608 TILs and counting..._
+_1609 TILs and counting..._
 
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@@ -691,6 +691,7 @@ If you've learned something here, support my efforts writing daily TILs by
 ### Mise
 
 - [List The Files Being Loaded By Mise](mise/list-the-files-being-loaded-by-mise.md)
+- [Read Existing Dot Env File Into Env Vars](mise/read-existing-dot-env-file-into-env-vars.md)
 
 ### MongoDB
 

mise/read-existing-dot-env-file-into-env-vars.md

@@ -0,0 +1,28 @@
+# Read Existing Dot Env File Into Env Vars
+
+Just about any web app that I've worked on has had a `.env` file as a way of
+configuring aspects of the app specific to that environment. These typically
+are read into the environment with a language-specific
+[dotenv](https://github.com/bkeepers/dotenv) tool.
+
+Mise supports this convention. In addition to specifying individual non-secret
+env vars, you can also instruct `mise` to read-in a `.env` file like so:
+
+```toml
+[env]
+PORT=3344
+_.file = ".env"
+```
+
+The `_.file` line tells `mise` that there is a file `.env` with key-value pairs
+that it should read in. It can even handle `.env.json` and `.env.toml` file
+formats.
+
+To ensure that `mise` is picking up the values from the `.env` file, you can
+run the following command and make sure they show up in the output:
+
+```bash
+$ mise env
+```
+
+[source](https://mise.jdx.dev/environments/secrets.html)