RE: [gentoo-user] Testing a used hard drive to make SURE it is good.

["Pengcheng Xu" <i@jsteward.moe>]

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I'm wondering that who's email client is broken, yours or mine?  I'm seeing a lot of U+FFFD replacement characters in this email, like, behind every stop punctuation ("?", ".", and ")"), but not in your other emails on the list.

Regards,
-- 
Pengcheng Xu
https://jsteward.moe

> -----Original Message-----
> From: Dale <rdalek1967@gmail.com>
> Sent: Thursday, June 18, 2020 5:14 PM
> To: gentoo-user@lists.gentoo.org
> Subject: Re: [gentoo-user] Testing a used hard drive to make SURE it is good.
> 
> David Haller wrote:
> 
> 
> 	Hello,
> 
> 	On Mon, 15 Jun 2020, Dale wrote:
> 	[..]
> 
> 		While I'm at it, when running dd, I have zero and random in /dev.�
> Where
> 		does a person obtain a one?� In other words, I can write all zeros,
> I
> 		can write all random but I can't write all ones since it isn't
> in /dev.�
> 		Does that even exist?� Can I create it myself somehow?� Can I
> download
> 		it or install it somehow?� I been curious about that for a good
> long
> 		while now.� I just never remember to ask.�
> 
> 
> 	I've wondered that too. So I just hacked one up just now.
> 
> 	==== ones.c ====
> 	#include <unistd.h>
> 	#include <stdlib.h>
> 	#include <stdio.h>
> 	static unsigned int buf[BUFSIZ];
> 	int main(void) {
> 	    unsigned int i;
> 	    for(i = 0; i < BUFSIZ; i++) { buf[i] = (unsigned int)-1; }
> 	    while( write(STDOUT_FILENO, buf, sizeof(buf)) );
> 	    exit(0);
> 	}
> 	====
> 
> 	Compile with:
> 	    gcc $CFLAGS -o ones ones.c
> 	or
> 	    gcc $(portageq envvar CFLAGS) -o ones ones.c
> 
> 	and use/test e.g. like
> 
> 	    ./ones | dd of=/dev/null bs=8M count=1000 iflag=fullblock
> 
> 	Here, it's about as fast as
> 
> 	    cat /dev/zero | dd of=/dev/null bs=8M count=1000 iflag=fullblock
> 
> 	(but only about ~25% as fast as
> 	    dd if=/dev/zero of=/dev/null bs=8M count=1000 iflag=fullblock
> 	for whatever reason ever, but the implementation of /dev/zero is
> 	non-trivial ...)
> 
> 	HTH,
> 	-dnh
> 
> 
> 
> I got it to compile, at least it created a file named ones anyway.� What I'm
> unclear about, where is the if= for dd in the command?� All the commands I've
> seen before has a if= and a of=.� The if for input and of for output or target.�
> I'm assuming that if I want to target sdb, I'd replace null with /dev/sdb.�
> 
> As I've posted before, even my scripting skills are minimal.� Surprised I got
> it to compile even.� lol� Just trying to make sure I don't mess up something.�
> I placed all this in the /root directory.� I'm assuming I can copy paste the
> commands above while in /root to make it work?� I'm asking because I haven't
> tried it yet.�
> 
> Thanks.
> 
> Dale
> 
> :-)� :-)�
> 
> 

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