How to use dd to fill a disk with a specific char?

Question

I know i can fill an entire disk with 0x0 like this:

dd if=/dev/zero of=/dev/sda bs=4k conv=notrunc

Is there a way to fill the entire disk with a char of my choice?

score 5 · Accepted Answer · answered Sep 27 '13 at 14:42

5

How about this:

yes "<char>" | dd of=/dev/sda bs=4k conv=notrunc

Substitute with character of your choice.

answered Sep 27 '13 at 14:42

Nikhil

2,298
13
14

2

Unfortunately `yes` adds EOL character. – Grzegorz Żur Sep 28 '13 at 07:22

Grzegorz Żur · Answer 2 · 2019-02-12T07:24:59.587

4

You can do it this way:

while true; do echo -n 'x'; done | dd of=/dev/sda bs=4k conv=notrunc iflag=fullblock

edited Feb 12 '19 at 07:24

answered Sep 28 '13 at 07:21

Grzegorz Żur

47,257
14
109
105

1

adding a iflag=fullblock ensures writes happen at 4k granularity. – Shehbaz Jaffer Feb 11 '19 at 21:53

score 2 · Answer 3 · edited Oct 16 '17 at 08:58

2

yes "" | tr "\n" "<char>" | dd of=/dev/sda <rest of dd parameters>
cat /dev/zero | tr "\0" "<char>" | dd of=/dev/sda <rest of dd parameters>
cat /dev/zero | sed "y/\0x00/<char>/" | dd of=/dev/sda <rest of dd parameters>

Where <char> is your chosen character

edited Oct 16 '17 at 08:58

martin clayton

76,436
32
213
198

answered Oct 16 '17 at 08:48

Tomasz Rochumski

31
2

How to use dd to fill a disk with a specific char?

3 Answers3