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sd_id128_randomize - Man Page

Generate 128-bit IDs


#include <systemd/sd-id128.h>

int sd_id128_randomize(sd_id128_t *ret);


sd_id128_randomize() generates a new randomized 128-bit ID and returns it in ret. Every invocation returns a new randomly generated ID. This uses the getrandom(2) kernel random number generator.

Note that sd_id128_randomize() always returns a UUID Variant 1 Version 4 compatible ID. It is hence guaranteed that this function will never return the ID consisting of all zero or all one bits (SD_ID128_NULL, SD_ID128_ALLF).

For more information about the "sd_id128_t" type, see sd-id128(3).

systemd-id128(1)'s new command may be used as a command line front-end for sd_id128_randomize().

Return Value

The call returns 0 on success (in which case ret is filled in), or a negative errno-style error code.


Functions described here are available as a shared library, which can be compiled against and linked to with the libsystemd pkg-config(1) file.

The code described here uses getenv(3), which is declared to be not multi-thread-safe. This means that the code calling the functions described here must not call setenv(3) from a parallel thread. It is recommended to only do calls to setenv() from an early phase of the program when no other threads have been started.


sd_id128_randomize() was added in version 187.

See Also

systemd(1), sd-id128(3), machine-id(5), getrandom(2), random(4), sd_id128_get_machine(3)

Referenced By

sd_bus_set_server(3), sd-id128(3), sd_id128_get_machine(3), systemd.directives(7), systemd.index(7).

systemd 256.2