Re: /dev/random and dd

On Tue, 21 May 2002 [email protected] wrote:

> Am I right then in thinking there's really no easy solution with Linux? (short of 
> leaving the dd running overnight, or mounting the HD in another (faster) machine...)

There are kerjillions of easy ways of doing it with Linux :).

You could write a simple program that uses standard library random
function for generating random data. That should be way faster than
/dev/*random as its should have a rather plainforward implementation.

Then you can direct its output to /dev/hda or use dd if you wish.

More than 5,6 megabytes under 3 seconds with the following:
--------------------------------------------------------
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>

int main(int argc, char *argv[]){
        int seed;
        if (argc != 2){
                printf ("Usage: %s [seed], "
                        "where seed can be any integer.\n", argv[0]);
                exit (1);
        }
        errno=0;
        if ((seed = atol(argv[1])) && !errno)
                srand(seed);
        else {
                printf ("Error: %s: %s\n", argv[1],
                        errno ? "Numerical result out of range." : "Not a  number.");
                exit (2);
        }
        while (1) printf("%d",rand());
}

Compile it with
gcc -o rand rand.c
and strip symbols with
strip -s rand
and you'll get a 3kB binary that should fit into tomsrtbt easily.

Usage:
rand 12347 | dd of=/dev/hda
or
rand 12347 > /dev/hda


Drop me a note if you need a smaller or faster version -- printf is
overhead, using library rand() is also overhead. I guess it can be done
under 1 kB and considerably faster than with stdlib rand(), as the latter
uses long integers.

Regards,
m