I bought an external drive to put an Ubuntu in it. I will use it in multiple computers to work.
Problem is, when I installed it, it remplaced my initial grub by an another one, and the result of this is if the external disk is ejected, the grub won't boot.
This is all my blocks :
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
And my partitions list :
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
The question is, do you know what I need to do to have my initial grub back, without the external disk ? And if I plug the disk, that the Ubuntu that is on this disk adds up on the grub list ? If it's not possible, is it possible to install a grup on that drive, so I would just need to switch the disk I boot up on start up ?