The command "cryptsetup luksFormat /dev/sdX" initializes a block device with the LUKS (Linux Unified Key Setup) header and format, prompting for a passphrase that will be used to protect the master encryption key. Once formatted, the device must be unlocked using "cryptsetup open" (or
"luksOpen"), which creates a mapped device-mapper device that can then be formatted with a standard filesystem and mounted. There is no standard "mkfs.luks" command, since LUKS operates below the filesystem layer.