Public bug reported:
Problem occurs with: bash 4.3-2ubuntu1, Ubuntu Trusty
Does not occur with: bash 4.2-5ubuntu3, Ubuntu 13.10
At a bash prompt, this command works instantly:
touch ~/test && grep thunder ~/test
But this equivalent command has failed to exit after ten minutes:
touch ~/test && cat ~/test | grep thunder
The problem is not with cat or with grep. For example, this command works
instantly:
ps aux > ~/test && grep thunder ~/test
But this equivalent command has failed to exit after ten minutes:
ps aux | grep thunder
This command also fails to exit:
ls -l /proc/*/fd/* | grep 9579047
The common factor here is the pipe.
All the commands above *do* exit when run in a terminal in an Ubuntu
guest session.
They also exit when run under strace from the beginning:
http://paste.ubuntu.com/7119748/
When strace is attached to a process that is not exiting, it is stuck on a read:
Process 26532 attached
read(0,
<cjwatson> you'd get this if the shell failed to close its ends of the
pipe it's constructed
ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: bash 4.3-2ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-16.36-generic 3.13.5
Uname: Linux 3.13.0-16-generic i686
NonfreeKernelModules: wl
ApportVersion: 2.13.3-0ubuntu1
Architecture: i386
CurrentDesktop: Unity
Date: Wed Mar 19 14:09:53 2014
InstallationDate: Installed on 2011-02-24 (1118 days ago)
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
SourcePackage: bash
UpgradeStatus: Upgraded to trusty on 2014-03-10 (9 days ago)
** Affects: bash (Ubuntu)
Importance: Undecided
Status: New
** Tags: apport-bug i386 trusty
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https://bugs.launchpad.net/bugs/1294678
Title:
grep waits forever for piped input
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