The first Linux distribution I used back in the 90s (Slackware 3.0 IIRC) used LILO as a bootloader. And many distros used LILO for years even when GRUB was becoming the "default" bootloader.
Moreover, in the early years of Linux it was common to boot Linux from another OS (i.e. DOS or Windows) instead of relying on a bootloader/dual booting. For example ...
This answer is for others out there that DocSalvager's answer doesn't work for.
I followed DocSalvager's use of ls to find the correct hard drive partition. In my case it was (hd0,msdos5).
Then I executed the following commands to get back to the normal grub boot loader screen.
grub rescue> set boot=(hd0,msdos5)
grub rescue> set prefix=(hd0,msdos5)...
This is a limitation imposed by having a very old BIOS and bootloader rather than Linux itself. The BIOS would only be able to access the first 1024 cylinders of the disk (see here for more information on what cylinders/heads/sectors are). This limitation would extend to bootloaders which, due to their simple nature, would not have their own disk drivers and ...
The boot flag is from ancient times, where you would indicate an MBR partition record as bootable, so you could indicate where the boot loader resided.
On modern OS'es this is widely unused, as the MBR consists of a minimal stage loader which bootstraps either into its own partition or jumps to another area on the disk where the boot loader code is kept. (...
Recovering from a grub rescue crash ...
grub rescue> does not support cd, cp or any other filesystem commands except its own variation of ls which is really a kind of find command.
So first, had to find the partition with the /boot directory containing the vmlinuz and other boot image files...
grub rescue> ls
(hd0,4) (hd0,3) (hd0,2) (hd0,1)
LILO was the de-facto standard for booting Linux on PCs before Grub, from a very early stage (MCC, one of the first Linux distributions, used it). Various other bootloaders were used contemporaneously. Loadlin was quite common; it booted Linux from DOS, and was even used in some configurations with umsdos to host a Linux environment in a DOS file system... ...
/boot contains files that aren't used by the operating system, but by its bootloader. You'll find both files of the bootloader itself (like /boot/grub/* for Grub) and the Linux kernel (/boot/vmlinuz*) and often an associated initrd or initramfs.
On a PC with legacy BIOS (as opposed to the newer UEFI found on most recent computers), the software ...
Another reason beside the mentioned BIOS problem is that a separate /boot partition allows the use of a file system for the / volume which the boot loader does not understand (without being limited to block list loading like with lilo).
The boot process can't find the root partition (the part of the disk, that contains the information for starting up the system), so you have to specify its location yourself.
I think you have to look at something like this article: how-rescue-non-booting-grub-2-linux
short: in this grub rescue> command line type
... to list all available devices, ...
This is usually fixed by running the scripts detect the installed operating systems and generate the boot loader's (grub2 in this case) configuration file. On CentOS 7, that should be grub2-mkconfig.
Check that windows is detected. Run grub2-mkconfig but discard its output:
$ sudo grub2-mkconfig > /dev/null
Generating grub configuration file ...
Strictly speaking, UUID is not addressing at all.
Addressing is very, very simple: read drive X sector Y - or else. Read memory address Z - or else. Addressing is simple, fast, leaves not much room for interpretation, and it's everywhere.
UUID is not addressing. Instead it's searching, finding, sometimes waiting for devices to appear, and also ...
BOOTING IS HARD
Booting... well... it really is the hardest part. Every time a computer boots it basically meets itself anew. It acquaints itself with its various parts, and for each one it meets it gains capability. But it has to pull itself up by its own bootstraps, so to speak, from square one every time.
When designing a boot process the trick is to ...
Seems like you should do grub2-mkconfig in the chroot instead of doing it outside. grub2-mkconfig uses grub-probe to detect real devices associated with mount points, while airootfs (archiso's rootfs) is loaded into the ram and doesn't have a canonical path.
So before installing grub and generating config, do this first:
arch-chroot /mnt /bin/bash
I'm assuming you're using GRUB2 as your bootloader. You can disable the timeout by opening the file /etc/default/grub and changing the value of GRUB_TIMEOUT:
will disable the timeout feature.
See here for more information and settings.
Following up on the answer by @terdon - when you do the test-step, and grub2-mkconfig does not find the Windows partition. Next, make sure you have the "ntfs-3g" package installed, so that your Linux system can read the Windows partition(s).
sudo yum install ntfs-3g
After installing that, when you run
sudo grub2-mkconfig > /dev/null
... you should ...
dd copies exactly count blocks of bs bytes, or 2880*512 bytes in total in this case(but see below). That will truncate or pad the concatenation of the two files to a fixed size (since /dev/zero gives as many zero bytes as required). 1440 kB is looks like the size of a 3.5" HD floppy disk, so perhaps someone wanted to make images that fit the floppy exactly.
The plain numbering scheme is not actually used in recent systems (with "recent" being Ubuntu 9 and later, other distributions may have adapted in that era, too).
You are correct in observing the root partition is set with the plain numbering scheme. But this only is a default or fall-back setting which is usually overridden with the very next command, such ...
You start at the beginning, square one.
I'm sorry but you wiped everything, that's a brutal command. Not only did you wipe out the linux install, but you took the windows data with it. What you did didn't just wipe stuff in the partitions (/dev/sda1, 2, etc.), it wiped the partition table too because it matched /dev/sda which is the drive device itself.
It sounds like you enabled the "fast boot" option in your BIOS setup which disables the F2 setup and F12 boot menu prompts.
Power-off your laptop and hold down the F2 key, then power it on for the BIOS setup utility. Disable "fast boot", save and reboot.
Peripherals are connected to the main processor via a bus. Some bus protocols support enumeration (also called discovery), i.e. the main processor can ask “what devices are connected to this bus?” and the devices reply with some information about their type, manufacturer, model and configuration in a standardized format. With that information, the operating ...
Up through mid 2.6 kernels, the x86 kernel was directly bootable if copied onto a floppy disk (as though it were a disk image).
This was, in fact, the original way of booting Linux.
If you look at the header of an x86 kernel today you see an error message that says booting from floppies like that doesn't work anymore.
You would need to edit the file /etc/default/grub. In this file you'll find an entry called GRUB_CMDLINE_LINUX_DEFAULT. This entry must be edited to control the display of the splash screen.
The presence of the word splash in this entry enables the splash screen, with condensed text output. Adding quiet as well, results in just the splash screen; which is ...
Given that UEFI was only defined in 2005 there is a bunch of legacy equipment out there that doesn't support the spec. To add UEFI to a standard distribution would require testing of two code paths instead of one, and not only is boot code notoriously finicky, it's one of the most irritatingly time consuming bits of code to test.
It depends on which boot-loader was installed. If its a standard Debian install it should be GRUB2.
Boot the computer with all disks containing bootable installations attached and powered.
you need to open Root Terminal application to open a terminal as root, then enter these commands:
apt-get install os-prober
if os-prober package is ...
PKCS#7 signature not signed with a trusted key
This message is typically coming from a piece of hardware. In your case it's likely the Nvidia graphics card that's emitting this.
This issue is discussed here in more detail, where 2 users were actually experiencing this issue, titled: PKCS Signature error/warnings running dmesg on Ubuntu Mate 18.04.
If you ...
Just to clarify: You're using grub2, correct?
In case Grub2 is installed in its own boot partition, you don't need to change anything. When it is not (which would be really strange), then you could technically retain the grub.cfg, and if your distribution has it, also /etc/grub.d.
/boot should be it's own partition, though.
If you run mount and see ...
I came across this issue when installing CentOS 7.0. Windows was not initially listed in the output of grub2-mkconfig.
In order to install ntfs-3g as suggested in another answer, I had to first install epel-release:
sudo yum install epel-release
Simply trying sudo yum --enablerepo epel install ntfs-3g resulted in a repository not found message.
That there is a /boot directory is historically determined and from there "fixed" in the Filesystem Hierarchy Standard. Having such a standard allows programs (and sysadmins) to expect certain files at certain locations. In this case the files associated with the boot process.
Having a /boot partition at the beginning of a disc made sense for older BIOS'es ...
GRUB (some of it) stays in the MBR.
GRUB (rest of it) are several files that are loaded, from /boot/grub (for example: that nice image that appears as a background in GRUB is not stored on the MBR)
The answer is considering an MBR setup, GRUB can be used in other setups.
In an EFI setup things get hairy, GRUB can be used, but so ...
There's another way: you can create a menu entry that tells GRUB to load another secondary grub.cfg, such as one from another Linux distro.
For example, I started with Gentoo Linux from which I installed GRUB2 into the MBR (the machine is too old for EFI).
I then installed NixOS, which I configured to generate grub.cfg in it's own /boot (separate from ...