Display dialogs from the command line/shell scripts. Return user-inserted values or 1 if error.
zenity --question
zenity --info --text="{{Hello!}}"
zenity --forms --add-entry="{{Name}}" --add-password="{{Password}}" --separator="{{;}}"
zenity --file-selection --directory
{{(echo "#1"; sleep 1; echo "50"; echo "#2"; sleep 1; echo "100")}} | zenity --progress