why can't `dd` access /dev/stdout?

Hi All,

I want to get a random number by accessing /dev/urandom. But I get an
error

$dd if=/dev/urandom of=/dev/stdout bs=4 count=1
dd: opening `/dev/stdout': No such file or directory

So, can't `dd` access the device /dev/stdout?

Best Regards,
PRC
Jul 3, 2008

PRC wrote:
Hi All,
>
I want to get a random number by accessing /dev/urandom. But I get an
error

Does one of these help?

dd if=/dev/urandom bs=4 count=1 | whatever_todo_with_binary_data

dd if=/dev/urandom bs=4 count=1 2>/dev/null | od -t x1 -An

dd if=/dev/urandom bs=4 count=1 2>/dev/null | od -t x4 -An


Janis

>
$dd if=/dev/urandom of=/dev/stdout bs=4 count=1
dd: opening `/dev/stdout': No such file or directory
>
So, can't `dd` access the device /dev/stdout?
>
Best Regards,
PRC
Jul 3, 2008

Wed, 02 Jul 2008 18:36:52 -0700, PRC wrote:

Hi All,
>
I want to get a random number by accessing /dev/urandom. But I get an
error
>
$dd if=/dev/urandom of=/dev/stdout bs=4 count=1 dd: opening
`/dev/stdout': No such file or directory
>
So, can't `dd` access the device /dev/stdout?
>
Best Regards,
PRC
Jul 3, 2008

I believe dd is close()'ing file descriptor 1, which corresponds to
stdout - so /dev/stdout ceases to exist for that process.

Fortunately, you can just use:

dd if=/dev/urandom bs=4 count=1

IW, dd's output defaults to stdout.

2008-07-03, 09:46(-04), Maxwell Lol:
[]
Insted of
dd if=/dev/urandom
You can also use
dd </dev/urandom
>
The if= and of= options provide a humorous backwards compatibility to JCL
I don't know of any reason to use them. Perhaps others do.

The of= one can be useful in combination with conv=notrunc
for shells that don't support 1<(csh).

See also the nonstandard (GNU only?) conv=excl/nocreat and
iflag/oflag.

--
S