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uuid

Create a new unique UUID value

UUID

NAME

uuid - create a new unique UUID value

SYNOPSIS

uuid([upper:bool, time:bool])

DESCRIPTION

The uuid_generate function creates a new universally unique identifier (UUID). The uuid will be generated based on high-quality randomness from /dev/urandom, if available. If it is not available, then uuid_generate will use an alternative algorithm which uses the current time, the local ethernet MAC address (if available), and random data generated using a pseudo-random generator.
The uuid_generate_random function forces the use of the all-random UUID format, even if a high-quality random number generator (i.e., /dev/urandom) is not available, in which case a pseudo-random generator will be substituted. Note that the use of a pseudo-random generator may compromise the uniqueness of UUIDs generated in this fashion.

The uuid_generate_time function forces the use of the alternative algorithm which uses the current time and the local ethernet MAC address (if available). This algorithm used to be the default one used to generate UUID, but because of the use of the ethernet MAC address, it can leak information about when and where the UUID was generated. This can cause privacy problems in some applications, so the uuid_generate function only uses this algorithm if a high-quality source of randomness is not available. To guarantee uniqueness of UUIDs generated by concurrently running processes, the uuid library uses global clock state counter (if the process has permissions to gain exclusive access to this file) and/or the uuidd daemon, if it is running already or can be be spawned by the process (if installed and the process has enough permissions to run it). If neither of these two synchronization mechanisms can be used, it is theoretically possible that two concurrently running processes obtain the same UUID(s). To tell whether the UUID has been generated in a safe manner, use uuid_generate_time_safe.

The UUID is 16 bytes (128 bits) long, which gives approximately 3.4x10^38 unique values (there are approximately 10^80 elementary particles in the universe according to Carl Sagan's Cosmos). The new UUID can reasonably be considered unique among all UUIDs created on the local system, and among UUIDs created on other systems in the past and in the future.

The time argument forces the use of the alternative algorithm which uses the current time and the local ethernet MAC address (if available). This algorithm used to be the default one used to generate UUID, but because of the use of the ethernet MAC address, it can leak information about when  and where  the UUID was generated.  This can cause privacy problems in some applications, so the uuid_generate function only uses this algorithm if a high-quality source of randomness is not available.

PARAMETERS

upper
If true, the result will be displayed in uppercase
time
Store the time in the result. The time can be extracted using the function: uuid_time(uuid)

RETURN

String value in uppercase or lowercase

EXAMPLES

uuid();
uuid(upper:true);

return

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30C3DA96-DDF1-11E7-AC50-00065B397ECD

SEE ALSO

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AUTHOR

Written by Pierre Laplante, <laplante@sednove.com>

MODIFICATIONS

1.0 2014-09-09 21:24:14 laplante@sednove.com available in version 5.97

Edit

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