My computer wouldn't boot today because it timed out while waiting for a disk by UUID. I had reformatted one of my disks last night, and apparently that changes the UUID -- this makes sense, it just hadn't occurred to me.

For some reason, the computer didn't boot despite giving me a prompt to continue with boot, so I had to use a live USB boot to resolve the issue. Consulting the man page for lsblk, I was able to find the new UUID for the disk which had been reformatted:

lsblk -o +UUID | grep "sdb1" | awk '{print $NF}'

Then I could use that to edit the fstab:

mount /dev/nvmen0p2 /mnt
arch-chroot /mnt
vim /mnt/etc/fstab