Hmmm...well I had not heard of /dev/random either... I see that SunOS has a /dev/random and a /dev/urandom symlink to it. I didn't find anything with man -k. I'll look around for some docs on this thing.

As for just writing zeroes once, yeah it's probably good enough if you don't have physical access to the disk. But to take a disk with sensitive data, write zeroes to it and then make it available to the web would give a security guy a heart attack.

Suppose a write operation failed because the disk is flakey? A good driver will detect that and arrange for the write to return -1. But bad drivers exist. And few programmers do a good job of checking return codes anyway. Later on, someone might get the data with a lucky read. And this line of "reasoning" applies equally to a disk that has been wiped a thousand times. Security guys think this way...