我买了一个外置驱动器，将 Ubuntu 放入其中。我将在多台计算机上使用它来工作。
问题是，当我安装它时，它用另一个 grub 替换了我最初的 grub，结果是如果弹出外部磁盘，grub 将无法启动。
这是我的所有积木：
lsblk Thu 20 Sep 2018 02:37:30 PM CEST
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 489.1G 0 disk
├─sda1 8:1 0 16M 0 part
├─sda2 8:2 0 488.2G 0 part
└─sda3 8:3 0 843M 0 part
sdb 8:16 0 931.5G 0 disk
├─sdb1 8:17 0 450M 0 part
├─sdb2 8:18 0 99M 0 part /boot/efi
├─sdb3 8:19 0 16M 0 part
├─sdb4 8:20 0 686.8G 0 part
├─sdb5 8:21 0 236.3G 0 part /
└─sdb6 8:22 0 7.9G 0 part [SWAP]
sdc 8:32 0 223.6G 0 disk
├─sdc1 8:33 0 23.3G 0 part
├─sdc2 8:34 0 7.9G 0 part
└─sdc3 8:35 0 192.3G 0 part
sr0 11:0 1 1024M 0 rom
我的分区列表：
Disk /dev/ram0: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram1: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram2: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram3: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram4: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram5: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram6: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram7: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram8: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram9: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram10: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram11: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram12: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram13: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram14: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/ram15: 64 MiB, 67108864 bytes, 131072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/sda: 489.1 GiB, 525112713216 bytes, 1025610768 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: D4080E08-6C49-4D5D-AFAC-8E0ED13DE19C
Device Start End Sectors Size Type
/dev/sda1 2048 34815 32768 16M Microsoft reserved
/dev/sda2 34816 1023879907 1023845092 488.2G Microsoft basic data
/dev/sda3 1023881216 1025607679 1726464 843M Windows recovery environment
Disk /dev/sdb: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 1EE8F2AF-A6B3-477E-B1C8-79858BA104CD
Device Start End Sectors Size Type
/dev/sdb1 2048 923647 921600 450M Windows recovery environment
/dev/sdb2 923648 1126399 202752 99M EFI System
/dev/sdb3 1126400 1159167 32768 16M Microsoft reserved
/dev/sdb4 1159168 1441523711 1440364544 686.8G Microsoft basic data
/dev/sdb5 1441523712 1937000447 495476736 236.3G Linux filesystem
/dev/sdb6 1937000448 1953523711 16523264 7.9G Linux swap
Disk /dev/sdc: 223.6 GiB, 240057409536 bytes, 468862128 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 02086807-3D19-4BE7-BEFE-13021ABC9846
Device Start End Sectors Size Type
/dev/sdc1 2048 48939547 48937500 23.3G Linux filesystem
/dev/sdc2 48941056 65540095 16599040 7.9G Linux swap
/dev/sdc3 65540096 468860927 403320832 192.3G Linux filesystem
问题是，你知道我需要做什么才能恢复我的初始 grub，而无需外部磁盘吗？如果我插入磁盘，该磁盘上的 Ubuntu 是否会添加到 grub 列表中？如果不可能，是否可以在该驱动器上安装一个 grup，所以我只需要切换启动时启动的磁盘？
答案1
在 Ubuntu 安装过程中，有一个步骤会询问您要将 Grub 安装在哪里。在此步骤中，您必须指示程序将安装在哪个驱动器上。
要想做你想做的事，你必须：
- 配置 BIOS 启动顺序，先放 USB 驱动器，然后再放内置 HDD。
- 在内置硬盘上安装 Grub和在您的外部驱动器中。您无法在 Grub 中动态添加或删除条目。
这样，每次你没有驱动器启动时，它都会在你的内置硬盘上获取 grub。但如果你插入外置驱动器，它应该会显示 grub。顺便说一句，如果你遇到 Grub 问题，请查看此工具。您可以使用它来恢复驱动器上的 Grub。
希望这有帮助，祝你好运。