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I've unchecked some wrong box in grub-customizer and now grub menu shows only windows. Can I boot Ubuntu using grub CLI and resolve this because I don't have Ubuntu live CD.I've even tried Super grub disk but it shows "BOOTMGR missing" error.Is there any other easier way to solve this problem which doesn't involve ubuntu live CD.

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You need to know the disk's UUID to boot Linux. –  hexafraction Jun 14 '12 at 20:31
    
If not Live CD, then maybe USB stick? –  kubahaha Jun 14 '12 at 21:16

1 Answer 1

up vote 2 down vote accepted

You can boot Ubuntu without a live CD, but it is a bit complicated. First you have to enter the grub command line: press c on the selection screen. you will probably have to load some modules:

insmod gzio
insmod part_msdos
insmod ext2

then set the root partition, this is not your real root but where the kernel is installed:

set root='(hdX,msdosX)

auto completion should help here. Set the kernel:

linux /boot/vmlinuz-3.2.0-XX-generic root=/dev/sdxX 

again use tab for auto completion for the kernel. You will probably have to guess device (after root=) , it is probably something like /dev/sda1, /dev/sdb1. You will have to try till you find the rigth one.

then the initrd:

initrd /boot/initrd.img-3.2.0-XX-generic 

make sure to use the version number matches the kernels one. and finaly:

boot

Your system should boot up now. You can try:

sudo update-grub

to fix your bootloader.

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I have windows on sda1 and with sdb1 it drops to shell as sdb1 doesn't exits. Can't I find sdxX with some command. and my root is (hd0,msdos5) and swap partition is (hd0,msdos6) and 1,2,3 for windows if it helps.I also wonder why it doesn't show (hd0,msdos4) with ls. Whether it really doesn't exit or its hidden? –  user70668 Jun 15 '12 at 6:12
    
hd0,msdos5 translates to /dev/sda5, so this is your root probably. hd0,msdos4 would be the container for the extended partitions. –  konairius Jun 15 '12 at 10:15
    
Thanks a lot !! –  user70668 Jun 15 '12 at 12:16

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