depclean script to protect installed kernels

[Goverp]

The following script will scan a directory such as /boot for kernels of the name "vmlinuz*" and generate an "emerge --depclean --exclude ..." command to prevent depcleaning the sys-kernel/gentoo-sources package slots for any of those kernels. You can pass depclean parameters on the command line, such as "--ask" in the usual way.

It doesn't handle /boot directories that need mounting before use. It's not intended to be secure or idiot proof, so it's only safe if your system has only one administrator, and that's you. It needs modification if you use a different set of kernel sources such as tuxonice or similar.

Enjoy. (or criticise)

[Zucca]

I just emerge --noreplace <kernel_package>:<slot/version>
It should keep installed kernels away from depclean.

EDIT: Haven't ran the script yet, but looks like on the last line you should have "$@" (with the double quotes) instead of $*. Also arrays aren't supported in /bin/sh (the posix/dash ones), so maybe shebang should be #!/bin/bash?

EDIT02: Also the "keep" array can be used without the last loop creating the --exclude switches: emerge --exclude "${keep[*]}"
--exclude can take multiple package atoms separated with space, and thus the whole argument for --exclude needs to be quoted.

Note that I haven't tested this yet... Just my observations. ;)
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..: Zucca :..

[Goverp]

Thanks for feedback.

[Goverp]

OK, here's the better version, one less loop (thanks Zucca). It's definitely OK for dash and it's ilk, no bashisms.
<edit> OOPS, forgot to check for errors such as unmounted /boot"</edit>

[figueroa]

I add the kernel versions I don't want depcleaned into /var/lib/portage/world. I keep two or more kernels on board, usually three or four. When I want a kernel source depcleaned, I remove it from world. I think this goes contrary to conventional wisdom, but it's what I do. I currently have:

[Goverp]

[Zucca]

Oh. My neurons didn't fire propely as I have quite a bad flu (tested negative for COVID-19, yay).
I thought keep was an array, but the syntax was missing an extra (). :P

I find it amusing that the output of file isn't very easily machine parseable, except for the -print0 which appends NULL-character after each filename so that one can cut out filenames containing special characters. Well. It helps some...

So I started to test if there was a clean way to parse file output...
I ended up here

[Goverp]

I did a bit of digging on this myself, when I realized my UEFI laptop setup had three kernels - vmlinuz, vmlinuz.old and vmlinuz.new, and of course those filenames don't tell you the version. Various web things say there's a chain of offsets in the kernel file that will lead you to the release and version strings; I wasn't interested in chasing them down, so I wondered if any packages might have done the work for me. (Hence discovering "file" does. AFAIK, file makes no guarantees about it's output, so my script can stop working at any new release, but it definitely shows "version " followed by the "uname-r" release string. Since I'm only supporting gentoo-sources, the script can rely on -gentoo appearing in the release name. As an aside, you also get the version datestamp information "uname -v", so it's possible to tie the booted kernel to the file from which it was booted (assuming there are no duplicates).
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Greybeard

[Zucca]

Yeah. That works as long as one hasn't specified CONFIG_LOCALVERSION.
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..: Zucca :..

[Goverp]

LOCALVERSION comes after the "-gentoo", so it works for me.
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Greybeard

[Zucca]

[figueroa]

[Goverp]

[Ant P.]