如何在Ubuntu20.04中向grub.cfg添加USB引导选项？

Question

我已经确认USB上有一个适当的Ubuntu可引导文件命令。USB插在笔记本电脑上。grub菜单在启动时会自动显示。

问题是没有从USB引导的选项。

现在我想编辑grub.cfg，使它包含USB引导选项。从这里我该怎么做？

另外，/boot/grub/grub.cfg：

#
# 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 $prefix/grubenv ]; then
  set have_grubenv=true
  load_env
fi
if [ "${initrdfail}" = 2 ]; then
   set initrdfail=
elif [ "${initrdfail}" = 1 ]; then
   set next_entry="${prev_entry}"
   set prev_entry=
   save_env prev_entry
   if [ "${next_entry}" ]; then
      set initrdfail=2
   fi
fi
if [ "${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 initrdfail {
    if [ -n "${have_grubenv}" ]; then if [ -n "${partuuid}" ]; then
      if [ -z "${initrdfail}" ]; then
        set initrdfail=1
        if [ -n "${boot_once}" ]; then
          set prev_entry="${default}"
          save_env prev_entry
        fi
      fi
      save_env initrdfail
    fi; fi
}
function recordfail {
  set recordfail=1
  if [ -n "${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$feature_default_font_path = xy ] ; then
   font=unicode
else
insmod part_gpt
insmod ext2
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
  search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2  e860e8f0-912f-4874-8f0f-97e343371f12
else
  search --no-floppy --fs-uuid --set=root e860e8f0-912f-4874-8f0f-97e343371f12
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_IN
  insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ] ; then
  set timeout=30
else
  if [ x$feature_timeout_style = xy ] ; then
    set timeout_style=menu
    set timeout=5
  # Fallback normal timeout code in case the timeout_style feature is
  # unavailable.
  else
    set timeout=5
  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
### 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=7
    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-e860e8f0-912f-4874-8f0f-97e343371f12' {
    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
    set root='hd0,gpt2'
    if [ x$feature_platform_search_hint = xy ]; then
      search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2  e860e8f0-912f-4874-8f0f-97e343371f12
    else
      search --no-floppy --fs-uuid --set=root e860e8f0-912f-4874-8f0f-97e343371f12
    fi
    linux   /boot/vmlinuz-5.13.0-27-generic root=UUID=e860e8f0-912f-4874-8f0f-97e343371f12 ro  quiet splash $vt_handoff
    initrd  /boot/initrd.img-5.13.0-27-generic
}
submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-e860e8f0-912f-4874-8f0f-97e343371f12' {
    menuentry 'Ubuntu, with Linux 5.13.0-27-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.13.0-27-generic-advanced-e860e8f0-912f-4874-8f0f-97e343371f12' {
        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
        set root='hd0,gpt2'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2  e860e8f0-912f-4874-8f0f-97e343371f12
        else
          search --no-floppy --fs-uuid --set=root e860e8f0-912f-4874-8f0f-97e343371f12
        fi
        echo    'Loading Linux 5.13.0-27-generic ...'
        linux   /boot/vmlinuz-5.13.0-27-generic root=UUID=e860e8f0-912f-4874-8f0f-97e343371f12 ro  quiet splash $vt_handoff
        echo    'Loading initial ramdisk ...'
        initrd  /boot/initrd.img-5.13.0-27-generic
    }
    menuentry 'Ubuntu, with Linux 5.13.0-27-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.13.0-27-generic-recovery-e860e8f0-912f-4874-8f0f-97e343371f12' {
        recordfail
        load_video
        insmod gzio
        if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
        insmod part_gpt
        insmod ext2
        set root='hd0,gpt2'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2  e860e8f0-912f-4874-8f0f-97e343371f12
        else
          search --no-floppy --fs-uuid --set=root e860e8f0-912f-4874-8f0f-97e343371f12
        fi
        echo    'Loading Linux 5.13.0-27-generic ...'
        linux   /boot/vmlinuz-5.13.0-27-generic root=UUID=e860e8f0-912f-4874-8f0f-97e343371f12 ro recovery nomodeset dis_ucode_ldr 
        echo    'Loading initial ramdisk ...'
        initrd  /boot/initrd.img-5.13.0-27-generic
    }
    menuentry 'Ubuntu, with Linux 5.11.0-37-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.11.0-37-generic-advanced-e860e8f0-912f-4874-8f0f-97e343371f12' {
        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
        set root='hd0,gpt2'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2  e860e8f0-912f-4874-8f0f-97e343371f12
        else
          search --no-floppy --fs-uuid --set=root e860e8f0-912f-4874-8f0f-97e343371f12
        fi
        echo    'Loading Linux 5.11.0-37-generic ...'
        linux   /boot/vmlinuz-5.11.0-37-generic root=UUID=e860e8f0-912f-4874-8f0f-97e343371f12 ro  quiet splash $vt_handoff
        echo    'Loading initial ramdisk ...'
        initrd  /boot/initrd.img-5.11.0-37-generic
    }
    menuentry 'Ubuntu, with Linux 5.11.0-37-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.11.0-37-generic-recovery-e860e8f0-912f-4874-8f0f-97e343371f12' {
        recordfail
        load_video
        insmod gzio
        if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
        insmod part_gpt
        insmod ext2
        set root='hd0,gpt2'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2  e860e8f0-912f-4874-8f0f-97e343371f12
        else
          search --no-floppy --fs-uuid --set=root e860e8f0-912f-4874-8f0f-97e343371f12
        fi
        echo    'Loading Linux 5.11.0-37-generic ...'
        linux   /boot/vmlinuz-5.11.0-37-generic root=UUID=e860e8f0-912f-4874-8f0f-97e343371f12 ro recovery nomodeset dis_ucode_ldr 
        echo    'Loading initial ramdisk ...'
        initrd  /boot/initrd.img-5.11.0-37-generic
    }
    menuentry 'Ubuntu, with Linux 5.8.0-43-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.8.0-43-generic-advanced-e860e8f0-912f-4874-8f0f-97e343371f12' {
        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
        set root='hd0,gpt2'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2  e860e8f0-912f-4874-8f0f-97e343371f12
        else
          search --no-floppy --fs-uuid --set=root e860e8f0-912f-4874-8f0f-97e343371f12
        fi
        echo    'Loading Linux 5.8.0-43-generic ...'
        linux   /boot/vmlinuz-5.8.0-43-generic root=UUID=e860e8f0-912f-4874-8f0f-97e343371f12 ro  quiet splash $vt_handoff
        echo    'Loading initial ramdisk ...'
        initrd  /boot/initrd.img-5.8.0-43-generic
    }
    menuentry 'Ubuntu, with Linux 5.8.0-43-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.8.0-43-generic-recovery-e860e8f0-912f-4874-8f0f-97e343371f12' {
        recordfail
        load_video
        insmod gzio
        if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
        insmod part_gpt
        insmod ext2
        set root='hd0,gpt2'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2  e860e8f0-912f-4874-8f0f-97e343371f12
        else
          search --no-floppy --fs-uuid --set=root e860e8f0-912f-4874-8f0f-97e343371f12
        fi
        echo    'Loading Linux 5.8.0-43-generic ...'
        linux   /boot/vmlinuz-5.8.0-43-generic root=UUID=e860e8f0-912f-4874-8f0f-97e343371f12 ro recovery nomodeset dis_ucode_ldr 
        echo    'Loading initial ramdisk ...'
        initrd  /boot/initrd.img-5.8.0-43-generic
    }
}

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

### BEGIN /etc/grub.d/10_linux_zfs ###
### END /etc/grub.d/10_linux_zfs ###

### 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 ###
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/30_uefi-firmware ###
menuentry 'UEFI Firmware Settings' $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 ###

Answer 1

一个简单的In :这是BIOS的工作，而不是GRUB的。

通常，计算机将有一个方法转到BIOS (或UEFI)设置页面，例如，ThinkVantage on ThinkPads。在BIOS设置页面上，将出现启动顺序更改设置。将USB放在顶部，然后重新启动计算机。

如果没有BIOS设置页面(罕见但不是零)，或者您的计算机无法检测USB可引导磁盘，请使用上面的答案。不要修改GRUB配置文件。

如果你能提供你的计算机的实际模型，我可以告诉你实际的步骤。否则，您还可以检查有关如何更改启动顺序的手册。

Answer 2

当您输入黑色GRUB屏幕时，按C键或转义键(ESC)访问命令提示符，然后输入以下命令(这将使您能够启动)：

grub> root (hd0,0)   # first harddrive, first partition
grub> find /[tab]    # type the slash then press [tab], and it will try to list files on this partition
Error 17: Cannot mount selected partition   # Oops no file system here
grub> root (hd0,1)   # first harddrive, second partition
grub> find /[tab]
Possible files are: lost+found var etc media ...   # That was my hard drive with my linux install
grub> root (hd1,0)   # second hard drive usually is the USB drive if you have only one internal drive
grub> find /[tab]
Possible files are: ldlinux.sys mydoc myfile mystick syslinux.cfg  # Bingo, that's the USB stick

现在，输入以下命令引导驱动器：

chainloader +1
boot

为了方便起见，将这些命令添加到GRUB配置中(通常在/boot/grub/menu.lst中)：

# to boot from a USB device
title    Boot USB drive
root     (hd1,0)
chainloader +1
boot

资料来源：https://help.ubuntu.com/community/BootFromUSB#:~:text=The%20easiest%20way%20to%20boot，键%20到%20输入%20命令%20模式.