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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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GRUB is confusing (lemmy.ca)

submitted 5 days ago by [email protected] to c/[email protected]

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hello,

I don't know if this is the right place to ask this question but could someone explain me how a UEFI system boots, I couldn't find a guide online. I want to know because I don't understand certain GRUB commands and how it get installed.

I just copy paste commands from Arch wiki and it just magically works without me knowing anything about it.

all the different distros use different grub command parameter and it's so confusing. eg, Arch and Gentoo.

Arch command: grub-install --target=x86_64-efi --efi-directory=esp --bootloader-id=GRUB Gentoo command: grub-install --efi-directory=/efi

why both command is different? exactly where does grub gets installed?

sorry if this is a naive question but i really don't understnad GRUB.

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[–] [email protected] 6 points 5 days ago* (last edited 5 days ago) (1 children)

Short answer to your last paragraph:
vmlinuz is the kernel. It ends with z instead of x, because it's z-compressed to save space. (I've heard that it's possible to use an uncompressed kernel for that 1ms faster boot time)
Initramfs (not intramuscular, which my autocorrect thinks is appropriate) is a small filesystem blob, "initial ram filesystem", meant to be loaded directly into ram to allow the kernel to talk to your hardware via drivers. It also has a lot of binaries needed to perform other tasks that need to run before the root filesystem is mounted.

[–] [email protected] 1 points 5 days ago* (last edited 5 days ago) (1 children)

Oh wait, I see that vmlinuz file has a version to it. I couldn't remember if vmlinuz was the kernel or not, because I used to have multiples of them, but these days I only have one.

[–] [email protected] 2 points 5 days ago* (last edited 5 days ago)

You have one per installed kernel. Not sure what (if any) automagic is common for removing old kernels, I guess this varies between distros, but at least on my computers, old kernel remain. At least the previous one, maybe more. It comes in handy in case a kernel upgrade breaks something, which it actually did recently on one of my laptops - makes it easier to boot from old kernel and revert.

EDIT: I just checked. I have just one on my daily driver. It's quite new, and I don't think I've had a kernel upgrade on that one, so it makes sense.

On my work laptop (the one with borked kernel upgrade) I have two.

So what you most likely have is one or more vmlinuz-version-numbers, and then simply a symlink named just vmlinuz to the version you boot from.