What Can You Use if the Computer Cannot Start From Its Boot Disk?
How to repair Ubuntu if it won't boot
Fix startup problems
Start-up problems. That moment when – having expected yourself to be getting on with your day's piece of work or entertainment – y'all detect yourself staring at a cryptic fault message, or even worse, a blank screen.
No matter how many times you press reset or restart, the aforementioned impenetrable bulwark blocks your path. And so, what tin can yous practise? Start-up problems come in all shapes and sizes, and they can be hard to rail down.
At that place are, however, some audio principles to utilize that will resolve many errors, and in this tutorial, we're going to wait at the tools and techniques required to troubleshoot most start-up problems. Y'all should start by examining how the boot process works.
This reveals that the boot process can be split into three broad stages centred around the Grub 2 boot loader: pre-Grub, Grub and post-Grub. Knowing this allows you to focus your troubleshooting efforts based on where in the procedure the error or freeze occurs.
Permit'due south offset at the kickoff. You switch on your PC. If power comes on, only zilch else happens, chances are you've a hardware issue to sort – if you recently poked around the innards of your PC, then check everything is continued correctly.
If not, unplug all external devices except your keyboard and effort once again. If this doesn't work, open the case carefully and disconnect your internal drives likewise. If the computer now boots to the splash screen, you lot can try reconnecting the internal drives and trying again; if you're now able to boot to the login screen, shut downwards your PC and start reconnecting your external peripherals to see if the problem has cleared itself or can be targeted to a single device, in which example try a unlike cable, or become online and Google for known boot problems involving that device.
If you're lucky, your motherboard volition emit a serial of beeps or flashing lights you can apply – over again by enlisting the aid of the internet – to identify the likely problem. This may involve replacing a component or something more drastic.
If yous're able to go equally far as your PC'due south splash screen, but and so your computer hangs or a 'missing operating organization' error message appears, then showtime recall dorsum to any contempo changes.
If you lot've overclocked your PC, eg, yous should at present enter the system EFI or BIOS and look for the option to load fail-condom defaults. Try rebooting again.
If this fails, then the trouble is likely to be with your hard drive, and and so the first places to look are the MBR and Chow. If Chow isn't prepare to automatically appear when your PC starts, endeavour rebooting while holding the Shift primal or tapping Esc to bring upwards the Grub boot menu to confirm information technology's non able to fifty-fifty load itself.
Jump to the Boot-Repair tool section in one case you lot've verified it's nowhere to exist plant.
If Grub is able to load, but can't find any bootable OS you'll discover yourself with a number of scenarios: you may exist presented with a basic command prompt such equally chow> or grub rescue>, which indicates i or more files required by Grub are missing or corrupt.
You may become a specific error bulletin or frozen splash screen, or you may just run into Grub and nothing else, indicating it can't even find the about basic information required to proceed.
If y'all press C you lot may be able to enter the Grub Concluding fashion to perform basic checks and repairs – you tin can try to manually initiate the kick by pressing Ctrl+Ten or F10, eg, or utilize the set control to review current settings and change bones settings such as the graphics way.
If the Grub menu appears, then the upshot may lie with its configuration file if things immediately grind to a halt later on yous select a menu selection, merely if Linux does start loading before grinding to a halt, the problem will lie with your operating system, in which instance skip to the Mail-Grub troubleshooting section.
If you're struggling to fix Grub issues by hand, or there's no sign of Grub on your system at all, then you'll need to enlist the services of your rescue media and the Kicking-Repair tool, which works with all Debian-based distros, including Ubuntu.
The Kicking-Repair tool itself will launch automatically when yous kick from a Kicking-Repair tool disc, but if you're unable to create it, but accept access to a Linux installation disc, use that in a live environment instead, then take hold of the Boot-Repair tool using the following commands:
$ sudo add together-apt-repository ppa:yannubuntu/kick-repair
$ sudo apt-go update
$ sudo apt-go install boot-repair
$ kicking-repair
The Kicking-Repair tool is focussed on those early boot problems acquired past the hard drive's boot sector, MBR and Grub. Information technology basically provides a convenient and user-friendly graphical front-end to the tools required to set up many bug.
The tool offers a 'Recommended repair' pick that promises to fix most frequent problems, or yous can click 'Avant-garde options' to run across what it can do and manually select specific fixes without getting your hands muddied in the Terminal.
The step-by-step guide (run across Tweak Boot-Repair tool Settings later in this guide) reveals what repairs and tweaks are possible, merely notation the tool is context-sensitive, and some options may be greyed out or missing depending on your setup.
The tool automatically generates a log of your organisation and that information technology attempts to do, which you lot tin then share on the Ubuntu user forums if necessary. Earlier attempting any advanced tweaks on your own, it pays to endeavor the recommended option first, then ask for aid on the forums using the output logs generated – this will ensure y'all choose the right option and don't cause more damage.
The Boot process
When you press your system's ability push, control is initially given to your PC'southward EFI or BIOS, which starts its diverse components, performs bones diagnostics tests and attempts to find a bootable device, which is typically the first hard drive.
In one case located, the BIOS or EFI looks for the Principal Boot Record (MBR) at the very beginning of the drive, which has a tiny program within that loads the next stage of the kicking loader, reading a file (eg e2fs_stage_1_5), which in plow is able to load the Chow boot loader.
A 'missing operating system' error at this point means you need your rescue disc for diagnostics as something is missing – either in Grub, the MBR or the drive itself. Once Grub loads successfully it reads a file chosen menu.lst, which contains the list of choices you see in the boot menu. Each entry basically identifies the drive, partition and file that contains the Linux kernel, plus RAM deejay file used past the kernel as information technology boots.
The entry will also contain whatsoever additional parameters passed to the kernel. Control is now passed to the kernel, which attempts to mount the root file organisation. This is a key moment, and if it fails you may get a kernel panic, or things might grind to a halt. If successful, information technology'll create a single procedure to run the /sbin/upstart file (other distros use init) – if this goes wrong, you'll get a panic, it may halt again or drop you lot into a root shell.
At this betoken, upstart starts running scripts and upstart events to start other services and eventually bring you to the logon screen.
Source: https://www.techradar.com/how-to/computing/how-to-boot-repair-ubuntu-1315203
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