On 03.12.12 15:35, l...@rule.lv wrote:
[...]
I stumbled upon a problem where multiple pipe redirection occasionally get
stuck when trying to get sha256 sum of a stream.
You can try to reproduce the problem if you have /usr/ports/shells/bash
installed (output redirection used in this command is possible only in
bash).
Create temporary test file with command: "dd if=/dev/urandom of=/tmp/file1
bs=1k count=10"
And the command I'm using is:
/usr/local/bin/bash -c 'cat /tmp/file1 | tee >(/sbin/sha256 >
/tmp/file1.sha256) > /tmp/file1.copy' ; echo $status
Command gets stuck about once in 20 executions.
top output when command gets stuck (irrelevant processes removed):
PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND
84073 HappyUser 1 52 0 17612K 2268K wait 0 0:00 0.00% bash
84154 HappyUser 1 52 0 10084K 844K fifoow 1 0:00 0.00% tee
And more strangely, I can reproduce this problem on 9.0-RELEASE and
7.4-RELEASE-p6, but couldn't reproduce on 8.2-RELEASE-p4.
It maybe couldn't gather more randomness from /dev/random?
The random(4) manpage suggests that there's (theoretically)
indeed a chance that it blocks - see the section about
'kern.random.sys.seeded'.
So in fact - when you think the command gets stuck - it's
probably not bash related at all.
cheers,
Frank Reppin
--
43rd Law of Computing:
Anything that can go wr
fortune: Segmentation violation -- Core dumped
_______________________________________________
freebsd-questions@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-questions
To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"
