Zeros and ones

Erik Trulsson ertr1013 at
Fri May 2 17:03:36 PDT 2003

On Fri, May 02, 2003 at 07:53:40PM -0400, Jerry McAllister wrote:
> Hi,
> This should be easy, but short of writing something specific to do it,
> I am not getting my head around how.
> It is easy and convenient to use /dev/zero to write out a number of
> zero bytes to somewhere - as in: 
>           dd if=/dev/zero of=zerofile bs=512 count=1770000
>                 or
>           dd if=/dev/zero of=/dev/da1 bs=512 count=1770000
> But, I would like to write all ones - as in 0xff or maybe some
> other pattern - as if there was a /dev/one also.
> Is there a nice way to do this using UNIXistic stringing existing
> stuff together?   Or do I have to write a little piece of code?

Of course there is a nice way. :-)

Try something like

tr '\000' '\377' < /dev/zero | dd of=onesfile bs=512 count=1770000

to get a file with all bits equal to one.

<Insert your favourite quote here.>
Erik Trulsson
ertr1013 at

More information about the freebsd-questions mailing list