Change UUID under Linux?

Those working with ordinary disks can do this simply with tune2fs and uuidgen.

Example: using a not currently mounted device /dev/sdb1

tune2fs /dev/sdb1 -U `uuidgen`

The new UUID will be immediately visible under

ls -l /dev/disk/by-uuid

if, say, you need to copy the value to /etc/fstab for automatic mount.

However, blkid will continue to (erroneously) report the old value until the cache is updated (on reboot, for example; though the cache may be bypassed with sudo blkid -c /dev/null).

Alternatively, the new UUID may be obtained via udev with

sudo lsblk -fo UUID /dev/sdb1

Those working with LVM disks might like to check the answer here.