How do I get dd command quiet

Basta · 04-14-2005, 04:40 AM

Is there a way to get the dd command quiet. I'm using the dd command to generate a 1k file with random data. I tried to use > /dev/null redirection but is still gives output to the screen. This is what I get:

$ dd if=/dev/urandom of=tesfile count=1 bs=1k > /dev/null
1+0 records in
1+0 records out

Your help is appreciated.

perfect_circle · 04-14-2005, 04:50 AM

Quote:

Originally posted by Basta
Is there a way to get the dd command quiet. I'm using the dd command to generate a 1k file with random data. I tried to use > /dev/null redirection but is still gives output to the screen. This is what I get:

$ dd if=/dev/urandom of=tesfile count=1 bs=1k > /dev/null
1+0 records in
1+0 records out

Your help is appreciated.

> only redirects stdout. Not stderr. Some programms use stderr to throw messeges, not only errors.
Try
dd if=/dev/urandom of=tesfile count=1 bs=1k &> /dev/null
to redirect both stdout and stderr to /dev/null

for more info on I/O redirections read here:
http://www.tldp.org/LDP/abs/html/io-redirection.html

Basta · 04-14-2005, 04:57 AM

Thanx, perfect_cicrle. That does the trick.

perfect_circle · 04-14-2005, 04:59 AM

If you like to keep the tradition use it like this, it has the same result

dd if=/dev/urandom of=tesfile count=1 bs=1k > /dev/null 2>&1

(redirect stdout to /dev/null and redirect stderr (file descriptor of stderr is 2) to stdout (file descriptor of stdout is 1) )

TimSmall · 11-30-2015, 03:57 AM

I found this thread on Google, and was hoping for something to copy-and-paste into a script. Didn't find it, so came up with this in case anyone else finds it useful.

vs. the previous solutions, it doesn't throw away the stderr from dd if the return code from dd was non-zero (i.e. dd was unhappy).

error=$( dd if=/dev/fazero of=/dev/null count=1 2>&1 ) ; ddrc=$? ; if [ $ddrc != 0 ] ; then echo dd exited with return code $ddrc ; echo error was $error ; fi