mjhjmtu

I recently reinstalled CentOS 7 on a lab/development machine. I wanted to keep the /home partition from the previous installation, so I manually configured the partitioning to allow me to do that. In the process, I accidentally also kept the previous installation's /boot partition.

After installation was successful, I have a very busy Grub2 boot screen. In addition to my "new" clean CentOS install, all of my old kernel images appear in the boot screen:

CentOS Linux (3.10.0-693.11.1.el7.x86_64) 7 (Core)
CentOS Linux (3.10.0-693.5.2.el7.x86_64) 7 (Core)
CentOS Linux (3.10.0-693.el7.x86_64) 7 (Core) <--- this is the new/reinstalled OS
CentOS Linux (3.10.0-693.11.1.el7.x86_64.debug) 7 (Core)
CentOS Linux (0-rescue-7859fc0fbe934b91b11ea69046b5d787) 7 (Core)
CentOS Linux (0-rescue-6c92bef5457049e5a42e5609c540d753) 7 (Core)
CentOS Linux (0-rescue-e7a05dc4cdda4e778a344945ef1ed391) 7 (Core)

Simply running package-cleanup won't work, because there is really only one kernel installed (as far as the new OS is concerned):

$ package-cleanup --oldkernels --count=1
No old kernels to remove

$ uname -r
3.10.0-693.el7.x86_64

$ rpm -qa kernel*
kernel-debug-devel-3.10.0-693.11.6.el7.x86_64
kernel-3.10.0-693.el7.x86_64
kernel-headers-3.10.0-693.11.6.el7.x86_64
kernel-tools-libs-3.10.0-693.el7.x86_64
kernel-tools-3.10.0-693.el7.x86_64

Thus, I don't believe this is a dupe of regular "how do I clean up my /boot partition?" questions (such as How do I safely delete old kernel versions in CentOS 7?)

Normally I'd be fine with just dealing with a messy Grub2 menu, but my /boot partition only has 11 MiB left, so I'm unable to update my kernel.

I'm not sure what is safe to delete from the /boot partition. How do I clean it up when package-cleanup won't?

You can use yum whatprovides /boot/* to determine which kernels are still installed and ones that are not owned by a package you can safely delete. However this assumes grub is being autoconfigured.

jdwolf's answer produced a listing of which packages (on the old system) that provided the entries in /boot/*, but it was a bit voluminous, and not immediately apparent what files were not pertinent to my reinstall of CentOS. And example of some of the output:

$ yum whatprovides /boot/*

kernel-3.10.0-693.5.2.el7.x86_64 : The Linux kernel
Repo : updates
Matched from:
Filename : /boot/config-3.10.0-693.5.2.el7.x86_64

kernel-3.10.0-693.el7.x86_64 : The Linux kernel
Repo : base
Matched from:
Filename : /boot/config-3.10.0-693.el7.x86_64

fwupdate-efi-9-8.el7.x86_64 : UEFI binaries used by libfwup
Repo : base
Matched from:
Filename : /boot/efi

[... truncated output ...]

But that led me to use rpm -q --whatprovides /boot/* instead, which was much more useful to determine if the file was needed:

$ rpm -q --whatprovides /boot/*
file /boot/config-3.10.0-693.11.1.el7.x86_64 is not owned by any package
file /boot/config-3.10.0-693.11.1.el7.x86_64.debug is not owned by any package
file /boot/config-3.10.0-693.5.2.el7.x86_64 is not owned by any package
kernel-3.10.0-693.el7.x86_64
file /boot/efi is not owned by any package
file /boot/elf-memtest86+-5.01 is not owned by any package
file /boot/grub is not owned by any package
grub2-common-2.02-0.65.el7.centos.2.noarch
[... truncated output ...]

Note that rpm -q --whatprovides doesn't print the name of the input file if it matches a package that provides it. But it does return 0 if the file is provided by a package, and 1 if the file is not provided by a package. Thus, solution was trivially:

$ for f in /boot/*; do rpm -q --whatprovides $f || rm -f $f; done
file /boot/config-3.10.0-693.11.1.el7.x86_64 is not owned by any package
file /boot/config-3.10.0-693.11.1.el7.x86_64.debug is not owned by any package
file /boot/config-3.10.0-693.5.2.el7.x86_64 is not owned by any package
kernel-3.10.0-693.el7.x86_64
file /boot/efi is not owned by any package
rm: cannot remove ‘/boot/efi’: Is a directory
file /boot/elf-memtest86+-5.01 is not owned by any package
[... truncated output ...]

$ ls -1 /boot
config-3.10.0-693.el7.x86_64
efi
grub
grub2
initramfs-3.10.0-693.el7.x86_64.img
symvers-3.10.0-693.el7.x86_64.gz
System.map-3.10.0-693.el7.x86_64
vmlinuz-3.10.0-693.el7.x86_64

After running grub2-mkconfig -o /boot/grub2/grub.cfg, my Grub menu is clean, and I have a clean /boot directory.

Note: It would probably have been better or safer to use find /boot -type f -exec ... (or perhaps find ... -xargs ...), but my solution worked fine enough since rm -f doesn't delete directories.