On 10/21/2013 01:12 PM, Christian Boltz wrote:
Hello,
Am Montag, 21. Oktober 2013 schrieb Dominique Leuenberger a.k.a. Dimstar:
The 'surprise' to most is not really dd's behavior, but the fact that /dev/random can 'run out of data', which is different to /dev/null.
/dev/null does not even start to run ;-)
# dd if=/dev/null of=/tmp/foo bs=100 count=1 0+0 records in 0+0 records out 0 bytes (0 B) copied, 7.7241e-05 s, 0.0 kB/s
Of course, you need /dev/zero. The special device /dev/null returns nothing. finger@larrylap:~> dd if=/dev/zero of=/tmp/foo bs=100 count=1 1+0 records in 1+0 records out 100 bytes (100 B) copied, 0.000614026 s, 163 kB/s finger@larrylap:~> dd if=/dev/urandom of=/tmp/foo bs=100 count=1 1+0 records in 1+0 records out 100 bytes (100 B) copied, 0.00104014 s, 96.1 kB/s finger@larrylap:~> dd if=/dev/random of=/tmp/foo bs=100 count=1 1+0 records in 1+0 records out 100 bytes (100 B) copied, 0.000995256 s, 100 kB/s I had enough entries in the entropy pool to get 100 items from /dev/random. These runs were done on 13.1-RC1 on a real machine. Larry Larry -- To unsubscribe, e-mail: opensuse-factory+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-factory+owner@opensuse.org