this post was submitted on 24 May 2025
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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, and some tweakable parameters.

❤️🐧

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[–] timhh@programming.dev 7 points 12 hours ago

Yeah but please don't actually use this. Use a proper UUID library that works cross-platform and lets you choose the UUID type and can be seeded etc.

[–] Redjard@lemmy.dbzer0.com 14 points 18 hours ago

boot_id seems to be static, probably set at boot.
So don't use it for a random uuid.

[–] bleistift2@sopuli.xyz 9 points 16 hours ago

That’s what you get when you define a file system as “a system that names things”.

[–] clif@lemmy.world 4 points 14 hours ago

This is awesome. Thank you

[–] kionite231@lemmy.ca 3 points 17 hours ago

Thank you so much for sharing this!

[–] pelya@lemmy.world 1 points 15 hours ago

Works in Termux on Android

[–] Hamartiogonic@sopuli.xyz 0 points 13 hours ago (1 children)

See also: /dev/null

It’s basically a black hole where you can throw anything.

[–] victorz@lemmy.world 5 points 13 hours ago (3 children)
cat /proc/sys/kernel/random/uuid | /dev/null
[–] Hamartiogonic@sopuli.xyz 1 points 9 hours ago (2 children)

That reminds me of the CPU stress test I ran many years ago.

dd if=/dev/random of=/dev/null

If you have 8 cores, just open 8 terminals, and run that code in each of them.

[–] lime@feddit.nu 2 points 9 hours ago* (last edited 9 hours ago)
for i in {1..n}  # where n == number of cores
do
  dd if=/dev/urandom of=/dev/null &
done

# to stop:
jobs -p | xargs kill
[–] YerbaYerba@lemm.ee 2 points 9 hours ago

/dev/urandom should stress the CPU more. /dev/random can be entropy limited

[–] henfredemars 2 points 11 hours ago (1 children)

The information will be evenly distributed upon its surface and some believe one day it will be be radiated back out into the rest of the system.

[–] Hamartiogonic@sopuli.xyz 2 points 9 hours ago

That's a horrifying concept. Better not think about it.