/dev/urandom

Quoting die (dot) net:

The character special files /dev/random and /dev/urandom (present since Linux 1.3.30) provide an interface to the kernel’s random number generator. File /dev/random has major device number 1 and minor device number 8. File /dev/urandom has major device number 1 and minor device number 9.

We can use either /dev/urandom or /dev/random to achieve this purpose.

$ cat /dev/urandom

This gives us content of the file. Let’s pipe this into tr (translate or delete characters, checkout the man page for more details; go deeper) to filter out only lower-case, upper-case letters and numbers.

$ cat /dev/urandom | tr -dc 'a-zA-Z0-9'

Now we need only 32 characters out of these filtered characters. Let’s use fold.

$ cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 32 | head -n 1

And at the end, just to make sure we find the first out of many filtered strings, we used head here.

So this will give you a UUID, always guaranteed random by your OS.

You can store in some variable using legacy bourne shell backticks `` or $() operator.

$ NEW_UUID=$(cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 32 | head -n 1)
$ echo $NEW_UUID
S23nWnMLnmnnpTf6cCkQG5MqvUuqMLwo

Thanks for staying till the end. Here’s a bashato for you.