I need to create a notification balloon message in Windows 7 from the Command prompt with custom text. I have searched Google and found shell32.
You may use NirCmd by Nir Sofer like this:
NirCmd.exe trayballoon [Title] [Balloon Text] [Icon File] [Timeout]
This does not seem to work for Windows 10. There you may use Toast.exe, which writes to the message area instead.
Toast.exe -t "Title text" -m "Message" -p NotificationImage.png
You have to turn on notifications for Toast.exe in the Windows 10 settings dialog under Settings > Notifications & Actions