My /etc/fstab doesn't include the disk the system booted from, basically because I made some changes and forgot to include this. The initial /boot and / directories are on different drives.I noticed this because when I upgrade the system and grub and kernel get updated the changes are made to the /boot directory under / which is not initial boot drive.How can I tell after boot with device was booted from and its directory?I want to mount it in /etc/fstab as /boot and delete or rename the boot directory under / to something else.
How to work out which drive and directory your system booted from if it is not mounted in /etc/fstab?
boot;partition;devices;fstab
The root filesystem is passed to the kernel upon boot using the root argument. So you should be able to:cat /proc/cmdlineand then look for root=/some/path, or perhaps root=UUID=longstring. For instance, I get:BOOT_IMAGE=/boot/kernel-genkernel-x86_64-4.4.0-sabayon root=UUID=18f3b5a1-3994-43ef-ad6d-cb4c86ff5f95 ro quiet splashIf it's a path, it should point to something recognizable (like /dev/sdb3). If it's a UUID, copy the UUID, and run:ls -la /dev/disk/by-uuid/[paste UUID here]That should point to a symlink, like:lrwxrwxrwx 1 root root 10 Apr 11 22:14 /dev/disk/by-uuid/06699502-fc90-48e4-86c2-cefdaf921e41 -> ../../sda4Which should tell you which drive it was (in my case, the 4th partition of sda, iow, /dev/sda4)