# Alternate value syntax (no colon) - use alternate if variable is set, otherwise empty
TEST10=${DEFINED_VAR+alternate}    # Result: "alternate"
TEST11=${EMPTY_VAR+alternate}      # Result: "alternate" (empty but set)
TEST12=${UNDEFINED_VAR+alternate}  # Result: "" (empty)
```

**Key differences:**
- `:-` vs `-`: The colon makes empty values trigger the fallback
- `:+` vs `+`: The colon makes empty values not trigger the alternate
- Default syntax (`-`): Use variable value or fallback
- Alternate syntax (`+`): Use alternate value or empty string

</details>
<details><summary>`run` - Command Substitution</summary><br>

Add the output of a command to one of your variables in your .env file.

```ini