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Manual Pages  — UUIDGEN


uuidgen – generate universally unique identifiers



uuidgen [-1] [-n count] [-o filename]


The uuidgen utility by default generates a single DCE version 1 universally unique identifier (UUID), also known as a globally unique identifier (GUID). The UUID is written to stdout by default. The following options can be used to change the behaviour of uuidgen:
  This option only has effect if multiple identifiers are to be generated and instructs uuidgen to not generate them in batch, but one at a time.
  This option controls the number of identifiers generated. By default, multiple identifiers are generated in batch. The upper hard limit is 2048 (see uuidgen(2) ).
  Redirect output to filename instead of stdout.

Batched generation yields a dense set of identifiers in such a way that there is no identifier that is larger than the smallest identifier in the set and smaller than the largest identifier in the set and that is not already in the set.

When generating the identifiers one at a time, the identifiers will be close to each other, but operating system latency and processing time will be reflected in the distance between two successive identifiers.


The utility exits 0 on success, and >0 if an error occurs.


uuidgen(2), uuid(3)


The uuidgen command first appeared in FreeBSD 5.0 .

UUIDGEN (1) May 23, 2012

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