feat: allow use system enviroment variables

config.go

@@ -67,6 +67,10 @@ func ParseConfig(data string, settings map[string]string) (Config, error) {
 			return val
 		}
 
+		if val, ok := os.LookupEnv(v); ok {
+			return val
+		}
+
 		return v
 	})
 

config_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"os"
 	"reflect"
 	"testing"
 )
@@ -15,6 +16,7 @@ windows:
     panes:
       - commands:
         - echo 2
+        - echo ${HOME}
         type: horizontal`
 
 	config, err := ParseConfig(yaml, map[string]string{
@@ -33,7 +35,7 @@ windows:
 				Panes: []Pane{
 					{
 						Type:     "horizontal",
-						Commands: []string{"echo 2"},
+						Commands: []string{"echo 2", "echo " + os.Getenv("HOME")},
 					},
 				},
 			},