GNU bug report logs - #18750
--line-buffered option doesn't work with --files-with-matches

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: tracker <at> debbugs.gnu.org
Subject: bug#18750: closed (--line-buffered option doesn't work with
 --files-with-matches)
Date: Thu, 31 Dec 2015 08:30:02 +0000

[Message part 1 (text/plain, inline)]

Your message dated Thu, 31 Dec 2015 00:29:46 -0800
with message-id <5684E77A.5000808 <at> cs.ucla.edu>
and subject line Re: --line-buffered option doesn't work with --files-with-matches
has caused the debbugs.gnu.org bug report #18750,
regarding --line-buffered option doesn't work with --files-with-matches
to be marked as done.

(If you believe you have received this mail in error, please contact
help-debbugs <at> gnu.org.)


-- 
18750: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=18750
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Contact help-debbugs <at> gnu.org with problems

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From: "Louis S." <sautier.louis <at> gmail.com>
To: bug-grep <at> gnu.org
Subject: --line-buffered option doesn't work with --files-with-matches
Date: Thu, 16 Oct 2014 23:16:30 +0200

Hi, I'm not quite sure this is a bug but it appears that the
--line-buffered option has no effect when used in conjunction with
--files-with-matches.
Here are some tests I ran with grep 2.20:
$ time for i in {1..100}; do grep --line-buffered -Rl gnome /usr/ |
head -n1 >& /dev/null; done
real    0m54.831s
user    0m37.077s
sys     0m17.550s

$ time for i in {1..100}; do grep -Rl gnome /usr/ | head -n1 >& /dev/null; done
real    0m54.858s
user    0m36.987s
sys     0m17.657s

$ time for i in {1..100}; do grep --line-buffered -R gnome /usr/ |
head -n1 >& /dev/null; done
real    0m7.414s
user    0m4.727s
sys     0m2.613s

Please let me know if line-buffering is supposed to work in that case.

Regards,

Louis

[Message part 3 (message/rfc822, inline)]

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: 18750-done <at> debbugs.gnu.org
Cc: "Louis S." <sautier.louis <at> gmail.com>, Norihiro Tanaka <noritnk <at> kcn.ne.jp>
Subject: Re: --line-buffered option doesn't work with --files-with-matches
Date: Thu, 31 Dec 2015 00:29:46 -0800

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Thanks for the bug report. It also seems to me that --line-buffered should apply 
to nulls, not newlines, when -z is used. Also, there are a couple of other 
places where stdout should get flushed after a newline. Perhaps we should use 
setvbuf instead (is it faster?) when -z is not also used, but right now I just 
want to get the bug fixed for the next release, so I installed the attached, 
more-conservative, patch, and am marking this bug as done.

[0001-grep-fix-l-line-buffer-bug.patch (text/x-diff, attachment)]

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