this post was submitted on 24 May 2025
87 points (96.8% liked)

Linux

7409 readers
311 users here now

A community for everything relating to the GNU/Linux operating system

Also check out:

Original icon base courtesy of lewing@isc.tamu.edu and The GIMP

founded 2 years ago
MODERATORS
Ategon@programming.dev
anzo@programming.dev
dwraf_of_ignorance@programming.dev
87
cat /proc/sys/kernel/random/uuid [I ❤️ Linux] (feddit.org)
submitted 22 hours ago by A_norny_mousse@feddit.org to c/linux@programming.dev
23 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, and some tweakable parameters.

❤️🐧

you are viewing a single comment's thread
view the rest of the comments
[–] Hamartiogonic@sopuli.xyz -1 points 16 hours ago (2 children)

See also: /dev/null

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

[–] DaPorkchop_@lemmy.ml 7 points 15 hours ago

Yes, but what if it were a subscription? May I present: /dev/null-as-a-Service.

[–] victorz@lemmy.world 6 points 15 hours ago* (last edited 1 hour ago) (4 children) 
cat /proc/sys/kernel/random/uuid > /dev/null
[–] DaPorkchop_@lemmy.ml 16 points 15 hours ago (2 children)

Would have to be cat /proc/sys/kernel/random/uuid > /dev/null

You can't pipe to a file, only to programs, and since /dev/null isn't an executable your command will simply give an error.

To make it more clear, consider using dd, which lets you explicitly specify an input and output file. For example: dd if=/proc/sys/kernel/random/uuid of=/dev/sda1 wait shit that wasn't the right output oh god oh fu

[–] victorz@lemmy.world 1 points 1 hour ago* (last edited 1 hour ago)

Thanks, I'm overworked lately.

lol, the last part

[–] sixtoe@lemmy.blahaj.zone 2 points 11 hours ago

i saw this and came to do THE THING but you beat me too it. GOOD ANYA

[–] henfredemars@infosec.pub 3 points 14 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 12 hours ago

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

[–] Hamartiogonic@sopuli.xyz 1 points 12 hours ago (3 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.

[–] victorz@lemmy.world 1 points 1 hour ago (1 children)

Can you guarantee that each process will run on its own core?

[–] Hamartiogonic@sopuli.xyz 1 points 5 minutes ago

Absolutely not, quite the opposite actually. However, the end result is close to 100% CPU load, which is good enough for some purposes. Let’s say you want to test the performance of your CPU cooler, or overclock stability, this should good enough. There are also dedicated tools for people with more advanced needs.

[–] YerbaYerba@lemm.ee 3 points 12 hours ago

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

[–] lime@feddit.nu 2 points 12 hours ago* (last edited 12 hours ago) (1 children) 
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
[–] Hamartiogonic@sopuli.xyz 1 points 3 minutes ago

Oh yeah. This looks like a much better way to do it. My solution is pretty bare bones by comparison.