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Erasing GPT backup header block, if expr is good enough

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This commit is contained in:
Thomas Schmitt
2020-01-07 16:47:41 +01:00
parent 43d5804db3
commit 5a335e5594
4 changed files with 123 additions and 50 deletions
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34
xorriso-dd-target/xorriso-dd-target.1
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@ -9,7 +9,7 @@
.\" First parameter, NAME, should be all caps
.\" Second parameter, SECTION, should be 1-8, maybe w/ subsection
.\" other parameters are allowed: see man(7), man(1)
.TH XORRISO-DD-TARGET 1 "Version 1.5.3, Jan 6, 2020"
.TH XORRISO-DD-TARGET 1 "Version 1.5.3, Jan 7, 2020"
.\" Please adjust this date whenever revising the manpage.
.\"
.\" Some roff macros, for reference:
@ -48,7 +48,7 @@ If a single plausible candidate is detected, then the program is willing to
copy a disk image file onto it. This will overwrite or make inaccessible the
previous partition table and all previous data content of the target device.
.br
\fBSuperuser power\fR is normally needed for filesystem type identification,
\fBSuperuser power\fR is often needed for filesystem type identification,
for possible unmounting, and for possible image writing.
Option \fB\-with_sudo\fR offers a way to gain this power only for those
tasks and to run the program elsewise with a normal user's power.
@ -173,13 +173,14 @@ sdc : NO : usb+ no_fs_while_not_su\-
Option \fB\-plug_test\fR triggers an interactive method to unambiguously
determine the intended target device candidate. It consists of 2 or 3 steps.
.br
\fBStep 1\fR is to have the intended storage device unplugged and
\fBStep 1\fR is to have the intended storage device \fBunplugged\fR and
to confirm this by pressing the Enter key at the program's prompt. The program
will then assess the list of not wanted devices.
.br
\fBStep 2\fR is to plug in the intended storage device and to confirm this
by pressing the Enter key a second time. The program will wait up to 10 seconds
for a disk\-like storage device which is not in the list of not wanted devices.
\fBStep 2\fR is to \fBplug in\fR the intended storage device and to
confirm this by pressing the Enter key a second time. The program will wait
up to 10 seconds for a disk\-like storage device which is not in the list of
not wanted devices.
The user may wait with key pressing until the device blinking looks like it
is ready.
.br
@ -270,9 +271,18 @@ Unmounted: /dev/sde2
.br
Performing:
.br
sudo /bin/dd if='debian\-live\-10.0.0\-amd64\-xfce.iso' of=/dev/sde bs=1M status=progress oflag=dsync ; sync
sudo /bin/dd if=/dev/zero of=/dev/'sde' bs=512 seek='245759999'
.br
count=1 status=none
.br
sudo /bin/dd if='debian\-live\-10.0.0\-amd64\-xfce.iso' of=/dev/'sde'
.br
bs=1M status=progress oflag=dsync ; sync
.br
... dd messages ...
.br
The first dd run shall erase a possible GPT backup header. It is performed only
if the local program "expr" can deal with the byte size of the device.
.SS
\fBShow commands for writing to a not advised device:\fR
.br
@ -326,7 +336,13 @@ AGAINST THE ADVICE BY THIS PROGRAM, a daring user could do:
.br
sudo /bin/umount /dev/sdd3
.br
sudo /bin/dd if='debian\-live\-10.0.0\-amd64\-xfce.iso' of=/dev/sdd bs=1M status=progress oflag=dsync ; sync
sudo /bin/dd if=/dev/zero of=/dev/'sdd' bs=512 seek='7864318'
.br
count=1 status=none
.br
sudo /bin/dd if='debian\-live\-10.0.0\-amd64\-xfce.iso' of=/dev/sdd
.br
bs=1M status=progress oflag=dsync ; sync
.br
BE SMART. BE CAUTIOUS. BEWARE.
.SS
@ -538,7 +554,7 @@ Thomas Schmitt <scdbackup@gmx.net>
.br
for libburnia\-project.org
.SH COPYRIGHT
Copyright (c) 2019 Thomas Schmitt
Copyright (c) 2019 \- 2020 Thomas Schmitt
.br
Permission is granted to distribute this text freely. It shall only be
modified in sync with the technical properties of xorriso\-dd\-target.