RTOS

1. Add these repositories manually to /etc/apt/sources.list file. To do so

  From command line enter 
  	sudo gedit /etc/apt/sources.list
  	
  And add these two lines at the end of the file
  
	deb http://ppa.launchpad.net/abogani/realtime/ubuntu precise main 
	deb-src http://ppa.launchpad.net/abogani/realtime/ubuntu precise main
	
2. Now run

	sudo apt-get update.

3. Now you need to install real time os from the internet:

	sudo apt-get install linux-realtime

4. Reboot your system, the GRUB should show the real-time OS.

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If your grub does not show the RTOS just installed in the list of available kernals, then you need to use boot-repair.

If you have only linux and it does not shows the kernal.

You need to just edit /etc/default/grub and remove 0 from the 

	GRUB_HIDDEN_TIMEOUT=0 <- remove O
			||
			\/	
	GRUB_HIDDEN_TIMEOUT=

Run sudo grub-update and reboot.