Grub

by Kulbir Saini on Fedora, Grub, Hacks, HowTo, Installation, Kernel, Tips - Tricks

How To: Install Fedora without CD or DVD

Note: If you are new to Fedora/Linux, I highly recommend the book “Fedora Linux Toolbox”

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Use Case

  1. When you don’t have CD / DVD drive on your system.
  2. You have Fedora DVD but your system has only a CD Drive.
  3. You don’t want to waste time and resources in burning iso on optical media.

Pre-requisites

  1. You have a Fedora DVD iso or rescue cd iso.
  2. You have a Linux installation on your system.
  3. You have a partition (FAT32, ext2, ext3) which you will not format while installing the new OS.

How to proceed

Let us assume you want to install Fedora 9 on your system and you have a Linux distro already installed on your system. You have downloaded the Fedora DVD iso (Fedora-9-DVD-i686.iso). And you have a FAT32/ext2/ext3 partition /stuff/ which you will not format during installation.

Step 1 : Move the Fedora DVD iso to /stuff/ directory.

[root@saini saini]# mv Fedora-9-DVD-i686.iso /stuff/ [Enter]

Step 2 : Mount Fedora DVD iso on /mnt/

[root@saini saini]# mount /stuff/Fedora-9-DVD-i686.iso /mnt/ -ro loop [Enter] (do as root)

Step 3 : Copy the initrd.img and vmlinuz to /boot/ partition

[root@saini saini]# cd /mnt/isolinux/ [Enter]
[root@saini isolinux]# cp initrd.img vmlinuz /boot/ [Enter] (do as root)

Step 4 : Create grub entry for booting into Fedora 9

Add these lines at the end of your /boot/grub/grub.conf file.

title Fedora 9 (New installation)
    kernel /vmlinuz
    initrd /initrd.img

Step 5 : Note the device having Fedora DVD iso

[root@saini saini]# df -h [Enter]
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda3              15G  9.5G  4.1G  70% /
/dev/sda8             135G  116G   13G  91% /stuff
/dev/sda5             4.8G  1.2G  3.4G  26% /home
/dev/sda1              99M   12M   82M  13% /boot

In this case /dev/sda8 contains Fedora DVD iso. Note this down as you need it later.

Step 6 : Reboot

Reboot your system and boot into the Fedora 9 (New installation) grub entry.

Step 7 : Install from hard disk

While in installation wizard, select “Hard drive” as installation method and choose /dev/sda8 as it contains the Fedora DVD iso. And rest is damn easy.

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by Kulbir Saini on Grub, Hacks, HowTo, Linux, Security

How To: Recover/Crack Root Password when Grub is Locked

The only essential thing is that you should have a Linux boot CD of the same operating system for which you want to crack root password. Some other Linux boot CD may work in some cases. If system is able to boot from the CD, it will take you to a command prompt as shown.

boot:

Type ‘linux rescue’ at this command prompt and enter as shown

boot: linux rescue [Enter]

It will take you to some interface with some questions, answer them properly. The system will go to temporary command prompt. Then issue the following commands

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[bash$] chroot /mnt/sysimage [Enter]
[bash$] cd /boot/grub [Enter]
[bash$] vi menu.lst [Enter]

Now in this file you can see a line beginning with the word ‘password’ remove this line and save the file.

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[bash$]exit
[bash$]exit

Now system will be rebooted and you can see the grub without a password. Don’t forget to remove the CD.

Press ‘e’ at boot screen and again by taking the pointer to the second line press e. Now you can see yourself on a command prompt. Remove ‘rhgb quiet’ from there and write single and press enter.

Now you will come back to the boot screen. Press ‘b’ and system will appear to boot and leave you in command line interface like this.

-bash2-$

Just type passwd like this

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-bash2-$ passwd [Enter]
new password:
retype new password:
passwd: All authentication updated successfully.

Now you have set a new password. Now exit from the shell and system will boot properly in graphical interface.

-bash2-$ exit [Enter]

If there is any error in the procedure please post your suggestions.