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cat /proc/sys/kernel/random/uuid [I ❤️ Linux] (feddit.org)

submitted 1 day ago* (last edited 20 hours ago) by A_norny_mousse@feddit.org to c/linux@programming.dev

34 comments fedilink hide all child comments

That's all. I just found this in a random script. Generates a random UUID every time it's called. I didn't know.

Of course I can also use uuidgen or pipe /dev/(u)random into something to get a random alphanumeric string - but this is built right into the kernel!

In /proc/sys/kernel/random/, there's also boot_id which ~~seems to do the same~~ is static, and some tweakable parameters.

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[–] lnxtx@feddit.nl 4 points 15 hours ago* (last edited 15 hours ago)

Interesting,
non-scientific speed test:

kernel 6.1.0-37-amd64:

$ time for i in $(seq 1 100000); do cat /proc/sys/kernel/random/uuid > /dev/null; done

real    3m53,388s
user    1m37,366s
sys     2m13,847s

$ for i in $(seq 1 100000); do cat /proc/sys/kernel/random/uuid ; done | wc -l
100000

vs. uuid 1.6.2-1.5+b11:

$ time for i in $(seq 1 100000); do uuid -v4 > /dev/null; done

real    4m44,854s
user    1m37,867s
sys     3m4,414s

$ for i in $(seq 1 100000); do uuid -v4 ; done | wc -l
100000

EDIT: I'm blind (wrong result).