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Date:      Sun, 3 May 2015 10:03:15 -0600 (MDT)
From:      Warren Block <>
To:        Polytropon <>
Cc:        "William A. Mahaffey III" <>, FreeBSD Questions !!!! <>
Subject:   Re: How to restore a USB drive converted to bootable
Message-ID:  <>
In-Reply-To: <>
References:  <> <441tiz3wrx.fsf@lowell-desk.lan> <> <>

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On Sat, 2 May 2015, Polytropon wrote:

> On Sat, 02 May 2015 09:20:09 -0453, William A. Mahaffey III wrote:
>> On 05/02/15 09:06, Lowell Gilbert wrote:
>>> "William A. Mahaffey III" <> writes:
>>>> I am about to do some OS installs (NetBSD & OpenBSD, as it happens) on
>>>> boxen under construction. I would also like to use UBCD on a flash
>>>> drive to memcheck those boxen prior to installation. If I prep a USB
>>>> thumb drive as either a bootable UBCD drive or an over-the-WWW
>>>> installer, I wipe out the drive for its original use. Is there a way
>>>> to restore the drive back to its original functionality if I wanted to
>>> Is "wipe the drive and reformat" what you need to hear, or do you have
>>> more requirements that you haven't made clear?
>> Wipe & reformat, preferably from CLI under FBSD 9.3R-p13 for
>> convenience, is what I'm after. Clearly creating a bootable UBCD or
>> installer will wipe out whatever was
>> there before, so I just want to get back to 'virgin' USB drive.
> In that case, the command
> 	# dd if=/dev/zero of=/dev/da0 bs=1m count=1
> should be fine. If there is any offending GPT metadata located
> at the end of the USB drive, estimate the size and also erase
> the last few MBs (use skip= to do so). There is no need to
> actually zero out the _whole_ drive.

It is easier to use gpart, and it will correctly remove whichever 
partitioning metadata is present:

gpart destroy -F <device>

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