lsblk
List block devices and their mount points
lsblk shows disks, partitions, and mount points in a tree view. Use lsblk -f to include filesystem type and UUID, needed for /etc/fstab entries.
Example
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 20G 0 disk
└─sda1 8:1 0 20G 0 part /
Tip: Type it yourself in the terminal below - reading is not the same as doing.