无法使用dpkg/更新系统、GRUB识别异常及内核配置失败问题求助

今天我发现自己没法安装gparted，甚至连检查系统更新都不行，总是弹出未知错误。我能看出核心问题是内核无法被移除，导致终端里运行的任何相关进程都被中断，我试过强制移除操作也没用。

另外还有个棘手的问题——我的操作系统识别不到GRUB引导程序。

下面是终端输出的完整错误信息：

Setting up grub-pc (2.06-2ubuntu12.1) ...

/var/lib/dpkg/info/grub-pc.config: 12: /etc/default/grub: Usage:: not found

dpkg: error processing package grub-pc (--configure):

installed grub-pc package post-installation script subprocess returned error exit status 127

Setting up linux-image-5.19.0-26-generic (5.19.0-26.27) ...

Setting up linux-image-5.15.0-56-generic (5.15.0-56.62) ...

dpkg: dependency problems prevent configuration of grub-efi-amd64-signed:

grub-efi-amd64-signed depends on grub-efi-amd64 | grub-pc; however:

Package grub-efi-amd64 is not installed.

Package grub-pc is not configured yet.

dpkg: error processing package grub-efi-amd64-signed (--configure):

dependency problems - leaving unconfigured

Processing triggers for linux-image-5.19.0-26-generic (5.19.0-26.27) ...

/etc/kernel/postinst.d/dkms:

• dkms: running auto installation service for kernel 5.19.0-26-generic

...done.

/etc/kernel/postinst.d/dracut:

dracut: Generating /boot/initrd.img-5.19.0-26-generic

/etc/kernel/postinst.d/zz-update-grub:

Sourcing file /etc/default/grub

/usr/sbin/grub-mkconfig: 12: /etc/default/grub: Usage:: not found

run-parts: /etc/kernel/postinst.d/zz-update-grub exited with return code 127

dpkg: error processing package linux-image-5.19.0-26-generic (5.19.0-26.27):

installed linux-image-5.19.0-26-generic package post-installation script subprocess returned error exit status 1

Processing triggers for linux-image-5.15.0-56-generic (5.15.0-56.62) ...

/etc/kernel/postinst.d/dkms:

• dkms: running auto installation service for kernel 5.15.0-56-generic

...done.

/etc/kernel/postinst.d/dracut:

dracut: Generating /boot/initrd.img-5.15.0-56-generic

/etc/kernel/postinst.d/zz-update-grub:

Sourcing file /etc/default/grub

/usr/sbin/grub-mkconfig: 12: /etc/default/grub: Usage:: not found

run-parts: /etc/kernel/postinst.d/zz-update-grub exited with return code 127

dpkg: error processing package linux-image-5.15.0-56-generic (5.15.0-56.62):

installed linux-image-5.15.0-56-generic package post-installation script subprocess returned error exit status 1

**Errors were encountered while processing:

grub-pc

grub-efi-amd64-signed

linux-image-5.19.0-26-generic

linux-image-5.15.0-56-generic

我完全搞不懂这一系列问题的根源是什么，有没有人能帮我解释清楚问题所在，以及给出具体的修复步骤？

备注：内容来源于stack exchange，提问作者Nikolaj Popov