Date: Mon, 3 Dec 2012 16:35:15 +0200 (EET) From: long@rule.lv To: freebsd-questions@freebsd.org Subject: bash pipe redirection gets stuck Message-ID: <23353.144.36.114.84.1354545315.squirrel@mail.rule.lv>
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Dear all, 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. Thanks for any pointers/explanations, Normunds
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