Debian

Hello,
I am posting the following questions here because I need them answered by people who have actually done a lot of work in GRUB. DO NOT GIVE ME GUESS ANSWERS PLEASE. Feel free to redirect me if this is not the right place to ask these questions.


I am really confused about these basic things. I need to get these things cleared up before I ask further questions in this forum.

I'm not the Grub expert that you are looking for but maybe I'll say a few things that might help. My forte is Solaris, SCO and Linux (but not boot loaders).

However, I have had to deal with a number of boot failures under Linux and Linux Appliances (eg, RSA boxes) so I know that Grub errors and corruptions can be fixed ("re-installed" boot loader).

Here's a link:

301 Moved Permanently

Also there's a project on the internet called Super Grub Disk (with a later version called Super Grub2 Disk) which provides all kinds of tools for Grub. I never go into battle against Grub without their bootable CD in my toolkit.

Also, Super Grub Disk To The Rescue! - What's a GRUB? - Tutorials - LinuxPlanet


Hope that helps and I hope that you get other responses.

GRUB is often packaged by distributions to make it easier to install and upgrade.

GRUB's very reason to exist is because it uses configuration files instead of finicky bits hardcoded inside the MBR or some other hard-to-access disk location. That's quite a feat for a mere bootloader -- reading files generally needs the OSes help. That's what makes GRUB so big and complicated (for a bootloader, anyway). That's also what makes grub so flexible.

Other bootloaders like lilo cannot actually access files before anything boots. It must cache its configuration in the MBR or some other difficult-to-read place before before it will take effect.

GRUB usually uses Windows' bootloader to load Windows. It doesn't have to overwrite it due to the way Windows stores it. A simple 'chainloader' command tells grub to load the MBR from the Windows partition and it can handle itself from there.

Sir, you didn't tell me why various distributions are provided for various OSes. Like Debian has its own version of GRUB which is different from Fedora. If GRUB can boot all Linux why cant there be only one single universal GRUB for all Linux ?

Also why does GRUB need to read the configuration files of Linux ? It doesn't do so with Windows so why can't it do the same for Linux ?

Also what is the difference between the GRUB offered at-:
GNU GRUB - Obtaining GRUB
and the GRUB that comes with every Linux distribution ?

---------- Post updated at 01:08 AM ---------- Previous update was at 01:03 AM ----------

Sir, I know that SuperGRUB can repair GRUB but can it install GRUB on a system without a Linux bootloader ?

How do you reckon that you installed Debian without also installing Grub?

What media did you use?

Ok, let's say a company like Redhat starts a new release. They might go to the grub site and download what ever grub is current. Then they start to work on a release making sure that every thing works together, testing the release on different platforms that they want to support and evntually they release. Well after they started work on the release, maybe the grub folks issue a release of grub. Redhat may not start over again. Redhat may decide that the grub they downloaded a week ago is still good enough. Meanwhile Debian decide to start a new release so they grab that somewhat later version of grub. Now Debian and Redhat have different version of grub. So what? They are both happy with the version they have. Now grub releases a even newer version of grub with improved IA-64 support. Well, Debian supports IA-64, they may want that newer release. Redhat does not support IA-64 so they don't care about improved IA-64 support. So Debian may choose to upgrade Grub while Redhat decides to pass on that version.

Even if all distros downloaded that same version of grub within a few minutes of each other it is possible that they might need to tweak the code a little. Redhat is partners with Dell and sees Dell's new hardware before the general public. If grub did not work on some new disk that Dell was about to release Redhat can't wait. They must fix grub immediately to protect the partnership.

Finally Grub is themed. When I interrupt the boot sequence and see the Grub screen I am looking at the RedHat logo. Debian does not want display that logo. They have their own logo.

This is not unique to grub. KDE, Gnome, CUPS, sendmail, and dozens of other packages are in the boat. And all of this software changes with different releases of a distro (which is the point of a release). We have nothing but Redhat where I work, but we have a lot of different releases. Even between two systems with, say Redhat 5.1 installed, one might have more rpm updates than the other. If Redhat put out a change to grub for 5.1, we might actually have two different grubs on two different Redhat 5.1 systems.

Most (I am tempted to say "all") Linux distros have picked Grub to be the bootloader of choice. They have very complete Grub support. Grub completely handles the Linux boot process. If I want to boot up into single user mode or disable some kernel feature I can interrupt grub, edit the configuration file and continue booting. I might want to disable a kernel feature permanently so I would need to edit the Grub configuration file. None of this is possible with Windows. All Grub can do is transfer control to partition that contains Windows. It can't pass parameters and modify the way that Windows boots up. Microsoft is unlikely to embrace Grub the way that Linux has. Linux could decide to give Grub the cold shoulder too and find some other way to configure the boot process, but that is also unlikey. Both OS's are likely to go down different paths.

I don't know what to tell you about your PC. I don't know what you are currently using to boot. In general, yes I think it's always possible to install Grub as an after thought. But any error on your part is likely to result in an unbootable system. I don't recommend that you try unless you don't mind rebuilding the system from scratch. Most people have old systems laying around... trying something like this on a test system is a good way to learn. I would not try this on my primary workstation though.

I used full set DvD's. But I know I didn't install GRUB because I purposefully skipped the installation step which installs GRUB. If you are wondering why I did this is because the Debian installer wanted to install GRUB in the MBR but my system boots from a ESP and there is no MBR. I have installed a old version of Debian(Squeeze) so I need to install the latest version of GRUB manually.