[Chromebooks] nabil2000:
grub.cfg, fstab examples...

First

Disk /dev/sdb: 931.5 GiB, 1000204885504 bytes, 1953525167 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: 807AFD80-12D5-03A5-60BF-1E60B544E900

Device Start End Sectors Size Type

/dev/sdb1 2048 206847 204800 100M BIOS boot

/dev/sdb2 206848 135235583 135028736 64.4G Linux filesystem

/dev/sdb3 135235584 286480383 151244800 72.1G Linux filesystem

/dev/sdb4 286480384 599062527 312582144 149.1G Microsoft basic data

/dev/sdb5 599062528 599984127 921600 450M Windows recovery environment

/dev/sdb6 599984128 1007575039 407590912 194.4G Microsoft basic data

/dev/sdb7 1007575040 1949327359 941752320 449.1G Microsoft basic data

/dev/sdb8 1949329408 1953103871 3774464 1.8G Linux swap

/dev/sdb9 1953105920 1953519615 413696 202M EFI System

$ sudo blkid /dev/sdb9

/dev/sdb9: LABEL="UEFI" UUID="B07A-6430" TYPE="vfat" PARTLABEL="Basic data partition" PARTUUID="f7ffc8f0-896a-01d2-78e0-eb63b544e900"

$ sudo blkid /dev/sdb3

/dev/sdb3: LABEL="UBUNTU16" UUID="8082d3f4-ec43-4310-af55-934b67078f05" TYPE="ext4" PARTLABEL="Basic data partition" PARTUUID="c0428fd0-896a-01d2-e843-2160b544e900"

$ sudo blkid /dev/sdb8

/dev/sdb8: TYPE="swap" PARTLABEL="Basic data partition" PARTUUID="0000e5a5-f7e0-c5fd-6ae9-f2754acb0100"

$ nano /etc/fstab

# <file system> <mount point> <type> <options> <dump> <pass>

# / was on /dev/sdc3 during installation

UUID=6e69ee53-1a57-4cb5-b46f-f0f079fdf666 / ext4

# /boot/efi was on /dev/sda2 during installation

UUID=B07A-6430 /boot/efi vfat defaults 0 1

# swap was on /dev/sdc1 during installation

UUID=0000e5a5-f7e0-c5fd-6ae9-f2754acb0100 none swap sw $

$ nano /boot/efi/EFI/ubuntu/grub.cfg

search.fs_uuid 3fcb8592-bcc3-cf01-3048-8592bcc3cf01 root hd1,gpt3

set prefix=($root)'/boot/grub'

configfile $prefix/grub.cfg

Second

Disk /dev/sda: 465.8 GiB, 500107861504 bytes, 976773167 sectors

Units: sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 4096 bytes

I/O size (minimum/optimal): 4096 bytes / 33553920 bytes

Disklabel type: gpt

Disk identifier: 4CACF8A0-B3A8-039F-283E-2B13EAECE700

Device Start End Sectors Size Type

/dev/sda1 2048 411647 409600 200M EFI System

/dev/sda2 411648 210208767 209797120 100G Microsoft basic data

/dev/sda3 210415616 337403903 126988288 60.6G Linux filesystem

/dev/sda4 337403904 430872575 93468672 44.6G Linux filesystem

/dev/sda5 430872576 435066879 4194304 2G Linux swap

/dev/sda6 435066880 624490495 189423616 90.3G Microsoft basic data

/dev/sda7 624490496 976766975 352276480 168G Microsoft basic data

/dev/sda8 210208768 210415615 206848 101M BIOS boot

Partition table entries are not in disk order.

$ sudo blkid /dev/sda1

/dev/sda1: LABEL="EFI" UUID="4579-67B0" TYPE="vfat" PARTLABEL="Basic data partition" PARTUUID="42f7ecf0-d3b5-01d0-78f6-7ba1da69e800"

$ sudo blkid /dev/sda3

/dev/sda3: LABEL="UBUNTU18" UUID="6e69ee53-1a57-4cb5-b46f-f0f079fdf666" TYPE="ext4" PARTUUID="99b3c3d8-2c44-488b-a130-fefb68abbe5d"

$ sudo blkid /dev/sda5

/dev/sda5: UUID="93471658-7099-45fc-ac61-75e09b4bf08f" TYPE="swap" PARTUUID="fdb07319-debf-4394-9e71-27b3bca2a9ac"

$ nano /etc/fstab

# <file system> <mount point> <type> <options> <dump> <pass>

# / was on /dev/sdc3 during installation

UUID=6e69ee53-1a57-4cb5-b46f-f0f079fdf666 / ext4

# /boot/efi was on /dev/sda2 during installation

UUID=4579-67B0 /boot/efi vfat defaults 0 1

# swap was on /dev/sdc1 during installation

UUID=93471658-7099-45fc-ac61-75e09b4bf08f none swap sw

$ nano /boot/efi/EFI/ubuntu/grub.cfg

search.fs_uuid 6e69ee53-1a57-4cb5-b46f-f0f079fdf666 root hd1,gpt3

set prefix=($root)'/boot/grub'

configfile $prefix/grub.cfg

Looking at the above examples, you can tease out where identifiers need be, usually the commands listed on previous posts would look after that, but sometimes they do not, so you need to amend / correct grub.cfg & fstab manually...

I hope this helps ;) :)