UUID generator
Random v4 and time-ordered v7 UUIDs, up to a hundred at a time.
Result
How many UUIDs to create is not set
Type a number from 1 to 100 in “How many”.
Calculated in your browser — nothing is sent to the server
Practice on a machine
Lab “Volume won't mount”
In a Linux terminal
uuidgen
# a new v4 UUID (uuid-runtime package)
cat /proc/sys/kernel/random/uuid
# the same from the kernel
lsblk -f
# file system UUIDs
sudo blkid /dev/sdb1
# a partition's UUID for /etc/fstab
Refer to partitions in /etc/fstab by UUID: /dev/sdX names can change between boots.
FAQ
Can two v4 UUIDs collide?
Practically no: the chance of one collision reaches 50 % only after 2.7·10¹⁸ identifiers, a billion UUIDs a second for 85 years.
v4 or v7: which one to choose?
v7 for a database primary key: values grow over time and land at the end of the index. But v7 reveals when a record was created; where that matters, use v4.
What is the difference between a UUID and a GUID?
None: GUID is Microsoft's name for a UUID. Windows usually writes it in uppercase.