feat: cd builtin

main.go

@@ -66,8 +66,9 @@ func main() {
 		switch cmdArgs[0] {
 		case "exit":
 			os.Exit(0)
-		}
-
+		case "cd":
+			os.Chdir(strings.Trim(cmdString, "cd "))
+		default:
 			cmd := exec.Command(cmdArgs[0], cmdArgs[1:]...)
 			cmd.Stderr = os.Stderr
 			cmd.Stdout = os.Stdout
@@ -75,6 +76,7 @@ func main() {
 			if err := cmd.Run(); err != nil {
 				fmt.Fprintln(os.Stderr, err)
 			}
+		}
 		readline.AddHistory(cmdString)
 	}
 }