Generate UUID v6

Generate a reordered time-based UUID v6 with improved sortability for databases.

Code

Utilities

t=$(( $(date +%s) * 10000000 + 0x01b21dd213814000 ))
r=$(od -An -tx1 -N8 /dev/urandom | tr -d ' \n')
printf '%08x-%04x-%04x-%04x-%s\n' \
  $(( (t >> 28) & 0xffffffff )) \
  $(( (t >> 12) & 0xffff )) \
  $(( (t & 0xfff) | 0x6000 )) \
  $(( (0x${r:0:4} & 0x3fff) | 0x8000 )) \
  "${r:4:12}"

Server

More Bash Snippets

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Generate UUID v3

Generate a name-based UUID v3 using MD5 hashing of namespace and name.

Generate UUID v4

Generate a random UUID v4 (Universally Unique Identifier).

Generate UUID v5

Generate a name-based UUID v5 using SHA-1 hashing of namespace and name.

Generate UUID v7

Generate a Unix timestamp-based UUID v7 with millisecond precision, ideal for database primary keys.

Array Difference

Find elements in the first array that are not present in the second array.