一、Grubby的参数

(base) [root@NewOSBC8 ~]# grubby --help
Usage: grubby [OPTION...]
      --add-kernel=kernel-path            add an entry for the specified kernel
      --args=args                         default arguments for the new kernel or new arguments for kernel being updated)
      --bad-image-okay                    don't sanity check images in boot entries (for testing only)
  -c, --config-file=path                  path to grub config file to update ("-" for stdin)
      --copy-default                      use the default boot entry as a template for the new entry being added; if the default is not a linux image, or if the kernel referenced by the default image does not exist, the
                                          first linux entry whose kernel does exist is used as the template
      --default-kernel                    display the path of the default kernel
      --default-index                     display the index of the default kernel
      --default-title                     display the title of the default kernel
      --env=path                          path for environment data
      --grub2                             configure grub2 bootloader
      --info=kernel-path                  display boot information for specified kernel
      --initrd=initrd-path                initrd image for the new kernel
  -i, --extra-initrd=initrd-path          auxiliary initrd image for things other than the new kernel
      --make-default                      make the newly added entry the default boot entry
      --remove-args=STRING                remove kernel arguments
      --remove-kernel=kernel-path         remove all entries for the specified kernel
      --set-default=kernel-path           make the first entry referencing the specified kernel the default
      --set-default-index=entry-index     make the given entry index the default entry
      --title=entry-title                 title to use for the new kernel entry
      --update-kernel=kernel-path         updated information for the specified kernel
      --zipl                              configure zipl bootloader
  -b, --bls-directory                     path to directory containing the BootLoaderSpec fragment files

Help options:
  -?, --help                              Show this help message

二、grubby修改内核启动顺序

1、查看当前所有内核详情

(base) [root@NewOSBC8 ~]# grubby --info=ALL
index=0
kernel="/boot/vmlinuz-4.19.0-240.23.35.el8_2.bclinux.x86_64+debug"
args="ro crashkernel=160M resume=/dev/mapper/bel_newosbc8-swap rd.lvm.lv=bel_newosbc8/root rd.lvm.lv=bel_newosbc8/swap rhgb quiet $tuned_params"
root="/dev/mapper/bel_newosbc8-root"
initrd="/boot/initramfs-4.19.0-240.23.35.el8_2.bclinux.x86_64+debug.img $tuned_initrd"
title="BigCloud Enterprise Linux (4.19.0-240.23.35.el8_2.bclinux.x86_64+debug) 8.2 (Core)"
id="ced6230f6fe049c493cd1845587c3c75-4.19.0-240.23.35.el8_2.bclinux.x86_64+debug"
index=1
kernel="/boot/vmlinuz-4.19.0-240.23.35.el8_2.bclinux.x86_64"
args="ro crashkernel=160M resume=/dev/mapper/bel_newosbc8-swap rd.lvm.lv=bel_newosbc8/root rd.lvm.lv=bel_newosbc8/swap rhgb quiet $tuned_params"
root="/dev/mapper/bel_newosbc8-root"
initrd="/boot/initramfs-4.19.0-240.23.35.el8_2.bclinux.x86_64.img $tuned_initrd"
title="BigCloud Enterprise Linux (4.19.0-240.23.35.el8_2.bclinux.x86_64) 8.2 (Core)"
id="ced6230f6fe049c493cd1845587c3c75-4.19.0-240.23.35.el8_2.bclinux.x86_64"
index=2
kernel="/boot/vmlinuz-4.19.0-240.23.11.el8_2.bclinux.x86_64"
args="ro crashkernel=160M resume=/dev/mapper/bel_newosbc8-swap rd.lvm.lv=bel_newosbc8/root rd.lvm.lv=bel_newosbc8/swap rhgb quiet $tuned_params"
root="/dev/mapper/bel_newosbc8-root"
initrd="/boot/initramfs-4.19.0-240.23.11.el8_2.bclinux.x86_64.img $tuned_initrd"
title="BigCloud Enterprise Linux (4.19.0-240.23.11.el8_2.bclinux.x86_64) 8.2 (Core)"
id="ced6230f6fe049c493cd1845587c3c75-4.19.0-240.23.11.el8_2.bclinux.x86_64"
index=3
kernel="/boot/vmlinuz-0-rescue-ced6230f6fe049c493cd1845587c3c75"
args="ro crashkernel=160M resume=/dev/mapper/bel_newosbc8-swap rd.lvm.lv=bel_newosbc8/root rd.lvm.lv=bel_newosbc8/swap rhgb quiet"
root="/dev/mapper/bel_newosbc8-root"
initrd="/boot/initramfs-0-rescue-ced6230f6fe049c493cd1845587c3c75.img"
title="BigCloud Enterprise Linux (0-rescue-ced6230f6fe049c493cd1845587c3c75) 8.2 (Core)"
id="ced6230f6fe049c493cd1845587c3c75-0-rescue"

2、设置内核启动顺序index值
(base) [root@NewOSBC8 ~]# grubby --set-default-index=1
The default is /boot/loader/entries/ced6230f6fe049c493cd1845587c3c75-4.19.0-240.23.35.el8_2.bclinux.x86_64.conf with index 1 and kernel /boot/vmlinuz-4.19.0-240.23.35.el8_2.bclinux.x86_64

3、查看默认启动内核信息
(base) [root@NewOSBC8 ~]# grubby --default-kernel
/boot/vmlinuz-4.19.0-240.23.35.el8_2.bclinux.x86_64