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[188.102.39.35]) by smtp.gmail.com with ESMTPSA id r1sm10280366wrz.30.2022.01.11.03.04.13 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 11 Jan 2022 03:04:14 -0800 (PST) Date: Tue, 11 Jan 2022 11:01:52 +0000 (UTC) From: Roderick To: questions@freebsd.org Subject: Re: dd and mbr In-Reply-To: <20220111104112.dd98218395b3edc567ab2031@sohara.org> Message-ID: <8e516e50-466b-c79d-d83e-774df471495b@gmail.com> References: <4af920fc-eff1-a92e-d36e-1ba97079864c@gmail.com> <20220111104112.dd98218395b3edc567ab2031@sohara.org> List-Id: User questions List-Archive: https://lists.freebsd.org/archives/freebsd-questions List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-questions@freebsd.org X-BeenThere: freebsd-questions@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed X-Rspamd-Queue-Id: 4JY79q3Z20z3Hmm X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20210112 header.b=fEXljYlx; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of hruodr@gmail.com designates 2a00:1450:4864:20::436 as permitted sender) smtp.mailfrom=hruodr@gmail.com X-Spamd-Result: default: False [-3.97 / 15.00]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2a00:1450:4000::/36:c]; FREEMAIL_FROM(0.00)[gmail.com]; TO_DN_NONE(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; DKIM_TRACE(0.00)[gmail.com:+]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; NEURAL_HAM_SHORT(-0.98)[-0.976]; RECEIVED_SPAMHAUS_PBL(0.00)[188.102.39.35:received]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; MID_RHS_MATCH_FROM(0.00)[]; DWL_DNSWL_NONE(0.00)[gmail.com:dkim]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20210112]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-0.99)[-0.994]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[questions@freebsd.org]; RCPT_COUNT_ONE(0.00)[1]; RCVD_IN_DNSWL_NONE(0.00)[2a00:1450:4864:20::436:from]; RCVD_TLS_ALL(0.00)[] X-ThisMailContainsUnwantedMimeParts: N Thanks. Your answer seems to be a real answer and not a wild proposal to do an experiment. After taking the device away and plugging it again, I still get the partition table. Also after plugging other device in between. Perhaps it is written again?! No, I do not want to use fdisk, gpart or anything else. I want to see dd doing what it must do. How could I rely in dd otherwise? Rod. On Tue, 11 Jan 2022, Steve O'Hara-Smith wrote: > On Tue, 11 Jan 2022 10:02:26 +0000 (UTC) > Roderick wrote: > >> >> The command: >> >> dd if=/dev/zero of=/dev/da0 >> >> does not delete the mbr, I still see the partition table with >> fdisk. My questions: > > It does delete the partition table, but fdisk is showing you cached > data - the clue is in this bit of the output: > > ******* Working on device /dev/ada0 ******* > parameters extracted from in-core disklabel are: > > I thought there was a way to get fdisk to read directly but I > can't find it in the man page now. > > -- > Steve O'Hara-Smith > >