Hi! I've been trying to wipe a partition table using 'dd' but having problems.

dd if=/dev/zero bs=1 seek=446 count=64 of=dd_image_file


This truncates the file to 64 bytes in size

I want to keep file size original (8GB) but wipe only the partition table which is 64 bytes in size and 446 bytes into the image file. I've tried variants, such as;

dd if=/dev/zero bs=64 seek=446 count=1 of=dd_image_file

etc. But everything thus far truncates my file. Can anyone point out what I'm doing wrong here with my dd command?

regards,

-LC

Is there data you want to keep on this drive? If not and your only wanting to remove the partition table, doing a simple:

dd if=/dev/random of=/device/path bs=512 count=1024

I'm just really confused what your trying to accomplish by wiping such a small partition table..

I have an image of my drive. I want to use 'dd' to wipe only the partition table, for test purpose. I know I can back up only partition table by;
dd if=/dev/drive bs=1 skip=446 count=64 of=partition_table


I thought I use 'dd' to wipe only range of data in a file, here the partition table. Can it not be done on a file, but only a physical device?

thank you,

-LC

Have you considered sfdisk? You can use that to dump the partition table to a file, make some changes and dump from the file back. Needs to be done as root user.

For example:

sfdisk -d /dev/hda >file.txt

sfdisk /dev/hda < file.txt

This is wrong since it would seek 446*64 bytes (bs=64)


This command is right. dd truncate the file mentioned by "of" by default.

i quote from the dd manpage

so all you need to do is add conv=notrunc

dd if=/dev/zero bs=1 seek=446 count=64 conv=notrunc of=dd_image_file

and it should work.