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

submitted 1 day ago* (last edited 6 hours ago) by A_norny_mousse@feddit.org to c/linux@programming.dev

33 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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[–] timhh@programming.dev 7 points 22 hours ago (1 children)

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.

[–] A_norny_mousse@feddit.org 2 points 7 hours ago* (last edited 6 hours ago)

Can you explain?
Use for what?
Also it is being seeded, according to the file urandom_min_reseed_secs which is also writeable. Here are the other files:

-r--r--r-- 1 root root 0 25. 5. 11:13 boot_id
-r--r--r-- 1 root root 0 25. 5. 11:19 entropy_avail
-r--r--r-- 1 root root 0 25. 5. 11:19 poolsize
-rw-r--r-- 1 root root 0 25. 5. 11:19 urandom_min_reseed_secs
-r--r--r-- 1 root root 0 25. 5. 11:19 uuid
-rw-r--r-- 1 root root 0 25. 5. 11:19 write_wakeup_threshold

edit: the type is always DCE/random