How to make a computer System Dual Boot (Windows and Ubuntu)

There are two different ways to make a system dual boot.

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1. Installing Ubuntu on Windows Machine 

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It is very easy to install Ubuntu on a windows machine.for doing that follow these steps:

1-> make a free drive for Ubuntu operating System.

2-> Insert Live(bootable) CD or USB and install Ubuntu inside the free drive.

3-> after installation remove your Live CD or USB.

4-> Boot your system now you can see options for select operating systems on the boot menu.Ubuntu will be the primary operating system if you dont select any other option then Ubuntu will be boot automatically.

if you want to start windows then select the windows option from the boot menu. 

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2.Installing window on Ubuntu machine

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This is also an easy task to install windows on Ubuntu.but the diffrence is that you have to repair the grub after installing the windows because windows assumes it's only OS on the machine and it replace the grub with its own boot loader and you have to replace boot loader with grub. for installing windows on Ubuntu follow these steps: 

1-> Boot your system by Ubuntu Live USB or CD.

2-> open Gparted partition Editor

3-> right click on the drive and select Resize/Move option.

4-> give new size in MBs and click on resize option.

5-> now you can see the selected volume is shrinked and free space is unallocated.

6-> Insert bootable windows CD/DVD  and restart the system.

7-> Boot system by bootable CD/DVD and install windows in the free unallocated space.this will create a new partition for windows and install windows in this partition.

8-> after installing windows remove bootable CD/DVD or USB and restart the system.

9-> now you can see your windows operating system will boot there is no option for selecting operating system in boot menu.

 Now repair grub for making system dual boot.

 

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Repair grub

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1-> boot from Ubuntu Live USB or CD.

2-> Mount your partition by command:

       sudo mount /dev/sda1 /mnt      // make sure that /dev/sda1 is the correct partition for your system 

3-> Bind other stuff:

      for i in /sys /proc /run /dev; do sudo mount --bind "$i" "/mnt$i"; done

 

4-> chroot into Ubuntu install:

       sudo chroot /mnt

5-> after doing this you are in Ubuntu install now update grub

      update-grub

6-> if you got any error then reinstall grub:

      grub-install /dev/sda

      update-grub

7-> if everything worked without error then you're all set and do      

      exit

     sudo reboot 

if you still having problem and now only Ubuntu is booted then reinstall grub by boot-repair. 

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 Reinstall grub by boot-repair

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1-> Open the terminal and run the following commands to install boot-repair

      

       sudo add-apt-repository ppa:yannubuntu/boot-repair

      sudo apt-get update

      sudo apt-get install boot-repair 

2-> open boot-repair

3-> click on advance option

4-> check Reinstall GRUB,Unhide boot menu, and create a Bootinfo summary(to get help by email or forum)

5-> Change the tab to Grub Location Tab and check The options OS to boot by default and place GRUB into sda

6->Press Apply and Reboot the system 

Now your System is dual boot when you start your system you can see the OS options on boot menu.you can select them and boot desire OS.