Thread: Re: What seed does random() use if setseed() is not called first?

Carl Sopchak <carl@sopchak.me> writes:
>     <p>There is one point about the documentation for random() and
>       setseed() that is missing.  What is used to seed random() if
>       setseed() isn't called first?  I assume it's something like
>       /dev/random or /dev/urandom, but that's just a guess.  Can someone
>       please enlighten me?</p>

We don't document this because it's platform- and version-dependent,
but yeah, generally /dev/urandom or local equivalent.

            regards, tom lane

Carl Sopchak <carl@sopchak.me> writes:
>     <p>Thank you for the quick reply!  But I wouldn't have bothered you
>       if the documentation stated something to the effect of "While it's
>       platform-dependent, if setseed() is not called, the random number
>       generator is generally seeded by whatever method the operating
>       system provides as a source of randomness, such as /dev/urandom on
>       Linux/Unix, or <???> on Windows."</p>

Hmm, I thought this already was documented, but it looks like not.
I'll see what I can do.

            regards, tom lane