Ubuntu开机启动项的增删改

一、在重组系统，或者不想开机启动有太多的内核项显示，可以通过修改grub.cfg内的内容进行更正。文件路径：/boot/grub/grub.cfg

二、grub.cfg的详细内容：

#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
  set have_grubenv=true
  load_env
fi
if [ "${next_entry}" ] ; then
   set default="${next_entry}"
   set next_entry=
   save_env next_entry
   set boot_once=true
else
   set default="0"
fi

if [ x"${feature_menuentry_id}" = xy ]; then
  menuentry_id_option="--id"
else
  menuentry_id_option=""
fi

export menuentry_id_option

if [ "${prev_saved_entry}" ]; then
  set saved_entry="${prev_saved_entry}"
  save_env saved_entry
  set prev_saved_entry=
  save_env prev_saved_entry
  set boot_once=true
fi

function savedefault {
  if [ -z "${boot_once}" ]; then
    saved_entry="${chosen}"
    save_env saved_entry
  fi
}
function recordfail {
  set recordfail=1
  if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}
function load_video {
  if [ x$feature_all_video_module = xy ]; then
    insmod all_video
  else
    insmod efi_gop
    insmod efi_uga
    insmod ieee1275_fb
    insmod vbe
    insmod vga
    insmod video_bochs
    insmod video_cirrus
  fi
}

if [ x$feature_default_font_path = xy ] ; then
   font=unicode
else
insmod part_gpt
insmod ext2
if [ x$feature_platform_search_hint = xy ]; then
  search --no-floppy --fs-uuid --set=root  743da019-6cf3-448f-a554-583f15751063
else
  search --no-floppy --fs-uuid --set=root 743da019-6cf3-448f-a554-583f15751063
fi
    font="/usr/share/grub/unicode.pf2"
fi

if loadfont $font ; then
  set gfxmode=auto
  load_video
  insmod gfxterm
  set locale_dir=$prefix/locale
  set lang=en_US
  insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ] ; then
  set timeout=30
else
  if [ x$feature_timeout_style = xy ] ; then
    set timeout_style=hidden
    set timeout=10
  # Fallback hidden-timeout code in case the timeout_style feature is
  # unavailable.
  elif sleep --interruptible 10 ; then
    set timeout=0
  fi
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
if background_color 44,0,30,0; then
  clear
fi
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
function gfxmode {
	set gfxpayload="${1}"
	if [ "${1}" = "keep" ]; then
		set vt_handoff=vt.handoff=1
	else
		set vt_handoff=
	fi
}
if [ "${recordfail}" != 1 ]; then
  if [ -e ${prefix}/gfxblacklist.txt ]; then
    if hwmatch ${prefix}/gfxblacklist.txt 3; then
      if [ ${match} = 0 ]; then
        set linux_gfx_mode=keep
      else
        set linux_gfx_mode=text
      fi
    else
      set linux_gfx_mode=text
    fi
  else
    set linux_gfx_mode=keep
  fi
else
  set linux_gfx_mode=text
fi
export linux_gfx_mode
menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-743da019-6cf3-448f-a554-583f15751063' {
	recordfail
	load_video
	gfxmode $linux_gfx_mode
	insmod gzio
	if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
	insmod part_gpt
	insmod ext2
	if [ x$feature_platform_search_hint = xy ]; then
	  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
	else
	  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
	fi
        linux	/vmlinuz-5.4.0-122-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro  quiet splash $vt_handoff
	initrd	/initrd.img-5.4.0-122-generic
}
submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-743da019-6cf3-448f-a554-583f15751063' {
	menuentry 'Ubuntu, with Linux 5.4.0-122-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.4.0-122-generic-advanced-743da019-6cf3-448f-a554-583f15751063' {
		recordfail
		load_video
		gfxmode $linux_gfx_mode
		insmod gzio
		if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
		insmod part_gpt
		insmod ext2
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
		else
		  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
		fi
		echo	'Loading Linux 5.4.0-122-generic ...'
	        linux	/vmlinuz-5.4.0-122-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro  quiet splash $vt_handoff
		echo	'Loading initial ramdisk ...'
		initrd	/initrd.img-5.4.0-122-generic
	}
	menuentry 'Ubuntu, with Linux 5.4.0-122-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.4.0-122-generic-recovery-743da019-6cf3-448f-a554-583f15751063' {
		recordfail
		load_video
		insmod gzio
		if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
		insmod part_gpt
		insmod ext2
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
		else
		  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
		fi
		echo	'Loading Linux 5.4.0-122-generic ...'
	        linux	/vmlinuz-5.4.0-122-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro recovery nomodeset dis_ucode_ldr 
		echo	'Loading initial ramdisk ...'
		initrd	/initrd.img-5.4.0-122-generic
	}
	menuentry 'Ubuntu, with Linux 5.4.0-121-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.4.0-121-generic-advanced-743da019-6cf3-448f-a554-583f15751063' {
		recordfail
		load_video
		gfxmode $linux_gfx_mode
		insmod gzio
		if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
		insmod part_gpt
		insmod ext2
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
		else
		  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
		fi
		echo	'Loading Linux 5.4.0-121-generic ...'
	        linux	/vmlinuz-5.4.0-121-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro  quiet splash $vt_handoff
		echo	'Loading initial ramdisk ...'
		initrd	/initrd.img-5.4.0-121-generic
	}
	menuentry 'Ubuntu, with Linux 5.4.0-121-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.4.0-121-generic-recovery-743da019-6cf3-448f-a554-583f15751063' {
		recordfail
		load_video
		insmod gzio
		if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
		insmod part_gpt
		insmod ext2
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
		else
		  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
		fi
		echo	'Loading Linux 5.4.0-121-generic ...'
	        linux	/vmlinuz-5.4.0-121-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro recovery nomodeset dis_ucode_ldr 
		echo	'Loading initial ramdisk ...'
		initrd	/initrd.img-5.4.0-121-generic
	}
	menuentry 'Ubuntu, with Linux 5.4.0-84-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.4.0-84-generic-advanced-743da019-6cf3-448f-a554-583f15751063' {
		recordfail
		load_video
		gfxmode $linux_gfx_mode
		insmod gzio
		if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
		insmod part_gpt
		insmod ext2
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
		else
		  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
		fi
		echo	'Loading Linux 5.4.0-84-generic ...'
	        linux	/vmlinuz-5.4.0-84-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro  quiet splash $vt_handoff
		echo	'Loading initial ramdisk ...'
		initrd	/initrd.img-5.4.0-84-generic
	}
	menuentry 'Ubuntu, with Linux 5.4.0-84-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.4.0-84-generic-recovery-743da019-6cf3-448f-a554-583f15751063' {
		recordfail
		load_video
		insmod gzio
		if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
		insmod part_gpt
		insmod ext2
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
		else
		  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
		fi
		echo	'Loading Linux 5.4.0-84-generic ...'
	        linux	/vmlinuz-5.4.0-84-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro recovery nomodeset dis_ucode_ldr 
		echo	'Loading initial ramdisk ...'
		initrd	/initrd.img-5.4.0-84-generic
	}
}

### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###

### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/20_memtest86+ ###
### END /etc/grub.d/20_memtest86+ ###

### BEGIN /etc/grub.d/30_os-prober ###
menuentry 'Windows Boot Manager (on /dev/nvme0n1p1)' --class windows --class os $menuentry_id_option 'osprober-efi-F21F-9028' {
	insmod part_gpt
	insmod fat
	if [ x$feature_platform_search_hint = xy ]; then
	  search --no-floppy --fs-uuid --set=root  F21F-9028
	else
	  search --no-floppy --fs-uuid --set=root F21F-9028
	fi
	chainloader /EFI/Microsoft/Boot/bootmgfw.efi
}
set timeout_style=menu
if [ "${timeout}" = 0 ]; then
  set timeout=10
fi
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/30_uefi-firmware ###
menuentry 'System setup' $menuentry_id_option 'uefi-firmware' {
	fwsetup
}
### END /etc/grub.d/30_uefi-firmware ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f  ${config_directory}/custom.cfg ]; then
  source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f  $prefix/custom.cfg ]; then
  source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###

三、默认拉起的内核版本代码片段：

menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-743da019-6cf3-448f-a554-583f15751063' {
	recordfail
	load_video
	gfxmode $linux_gfx_mode
	insmod gzio
	if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
	insmod part_gpt
	insmod ext2
	if [ x$feature_platform_search_hint = xy ]; then
	  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
	else
	  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
	fi
        linux	/vmlinuz-5.4.0-122-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro  quiet splash $vt_handoff
	initrd	/initrd.img-5.4.0-122-generic
}

只需将：

linux    /vmlinuz-5.4.0-122-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro  quiet splash $vt_handoff
initrd    /initrd.img-5.4.0-122-generic

两行的内容换成自己想要版本的内核即可，后续开机默认开启的即为所选内核。

四、advance选项中的个内核版本的选择展示内容：

submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-743da019-6cf3-448f-a554-583f15751063' {
	menuentry 'Ubuntu, with Linux 5.4.0-122-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.4.0-122-generic-advanced-743da019-6cf3-448f-a554-583f15751063' {
		recordfail
		load_video
		gfxmode $linux_gfx_mode
		insmod gzio
		if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
		insmod part_gpt
		insmod ext2
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
		else
		  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
		fi
		echo	'Loading Linux 5.4.0-122-generic ...'
	        linux	/vmlinuz-5.4.0-122-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro  quiet splash $vt_handoff
		echo	'Loading initial ramdisk ...'
		initrd	/initrd.img-5.4.0-122-generic
	}
	menuentry 'Ubuntu, with Linux 5.4.0-122-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.4.0-122-generic-recovery-743da019-6cf3-448f-a554-583f15751063' {
		recordfail
		load_video
		insmod gzio
		if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
		insmod part_gpt
		insmod ext2
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
		else
		  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
		fi
		echo	'Loading Linux 5.4.0-122-generic ...'
	        linux	/vmlinuz-5.4.0-122-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro recovery nomodeset dis_ucode_ldr 
		echo	'Loading initial ramdisk ...'
		initrd	/initrd.img-5.4.0-122-generic
	}
	menuentry 'Ubuntu, with Linux 5.4.0-121-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.4.0-121-generic-advanced-743da019-6cf3-448f-a554-583f15751063' {
		recordfail
		load_video
		gfxmode $linux_gfx_mode
		insmod gzio
		if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
		insmod part_gpt
		insmod ext2
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
		else
		  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
		fi
		echo	'Loading Linux 5.4.0-121-generic ...'
	        linux	/vmlinuz-5.4.0-121-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro  quiet splash $vt_handoff
		echo	'Loading initial ramdisk ...'
		initrd	/initrd.img-5.4.0-121-generic
	}
	menuentry 'Ubuntu, with Linux 5.4.0-121-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.4.0-121-generic-recovery-743da019-6cf3-448f-a554-583f15751063' {
		recordfail
		load_video
		insmod gzio
		if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
		insmod part_gpt
		insmod ext2
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
		else
		  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
		fi
		echo	'Loading Linux 5.4.0-121-generic ...'
	        linux	/vmlinuz-5.4.0-121-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro recovery nomodeset dis_ucode_ldr 
		echo	'Loading initial ramdisk ...'
		initrd	/initrd.img-5.4.0-121-generic
	}
	menuentry 'Ubuntu, with Linux 5.4.0-84-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.4.0-84-generic-advanced-743da019-6cf3-448f-a554-583f15751063' {
		recordfail
		load_video
		gfxmode $linux_gfx_mode
		insmod gzio
		if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
		insmod part_gpt
		insmod ext2
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
		else
		  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
		fi
		echo	'Loading Linux 5.4.0-84-generic ...'
	        linux	/vmlinuz-5.4.0-84-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro  quiet splash $vt_handoff
		echo	'Loading initial ramdisk ...'
		initrd	/initrd.img-5.4.0-84-generic
	}
	menuentry 'Ubuntu, with Linux 5.4.0-84-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.4.0-84-generic-recovery-743da019-6cf3-448f-a554-583f15751063' {
		recordfail
		load_video
		insmod gzio
		if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
		insmod part_gpt
		insmod ext2
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root  b2ea8059-bc58-4d09-b036-d52117de2ffe
		else
		  search --no-floppy --fs-uuid --set=root b2ea8059-bc58-4d09-b036-d52117de2ffe
		fi
		echo	'Loading Linux 5.4.0-84-generic ...'
	        linux	/vmlinuz-5.4.0-84-generic root=UUID=743da019-6cf3-448f-a554-583f15751063 ro recovery nomodeset dis_ucode_ldr 
		echo	'Loading initial ramdisk ...'
		initrd	/initrd.img-5.4.0-84-generic
	}
}

其中每个menuentry包含的都为一个对应的版本内核，实际可以根据自身情况进行顺序调整或者增删。在自己安装的内核版本若是通过uname -a 可以查询到，但是在开机引导向不存在的情况下，也可以将其内核嵌套入此段代码中。