cmd/create: Require valid terminal when prompting to pull an image

To limit the possible misbehaviour of Toolbx when ued in scripting,
require the presence of valid terminal on stdin when an image needs to
be pulled to create a new toolbx.

src/cmd/create.go

@@ -63,6 +63,8 @@ var (
 		{"/etc/profile.d/toolbox.sh", "/etc/profile.d/toolbox.sh"},
 		{"/etc/profile.d/toolbox.sh", "/usr/share/profile.d/toolbox.sh"},
 	}
+
+    errorNotTerminal = errors.New("terminal is not connected")
 )
 
 var createCmd = &cobra.Command{
@@ -219,6 +221,15 @@ func createContainer(container, image, release, authFile string, showCommandToEn
 
 	pulled, err := pullImage(image, release, authFile)
 	if err != nil {
+        if errors.Is(err, errorNotTerminal) {
+            var builder strings.Builder
+            fmt.Fprintf(&builder, "User interaction required to pull a new image. Stopping now.\n")
+            fmt.Fprintf(&builder, "Run '%s --help' for usage.", executableBase)
+
+            errMsg := builder.String()
+            return errors.New(errMsg)
+        }
+
 		return err
 	}
 	if !pulled {
@@ -722,9 +733,13 @@ func pullImage(image, release, authFile string) (bool, error) {
 	}
 
 	promptForDownload := true
-	var shouldPullImage bool
+    shouldPullImage := false
+
+    if !term.IsTerminal(os.Stdin) {
+        return false, errorNotTerminal
+    }
 
-	if rootFlags.assumeYes || domain == "localhost" {
+    if rootFlags.assumeYes || domain == "localhost" {
 		promptForDownload = false
 		shouldPullImage = true
 	}