GNU bug report logs - #19899
deleting lines of a file with sed - unexpected behaviour

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Ethan Kaufman <ethan.kaufman <at> gmail.com>
Subject: bug#19899: closed (Re: bug#19899: sed: fix mishandling of
 overlapping address ranges)
Date: Thu, 07 May 2015 02:22:02 +0000

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Your bug report

#19899: deleting lines of a file with sed - unexpected behaviour

which was filed against the sed package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 19899 <at> debbugs.gnu.org.

-- 
19899: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=19899
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Jim Meyering <jim <at> meyering.net>
To: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
Cc: 19899-done <at> debbugs.gnu.org, Ethan Kaufman <ethan.kaufman <at> gmail.com>
Subject: Re: bug#19899: sed: fix mishandling of overlapping address ranges
Date: Wed, 6 May 2015 19:20:47 -0700

On Tue, May 5, 2015 at 4:39 PM, Norihiro Tanaka <noritnk <at> kcn.ne.jp> wrote:
> On Mon, 4 May 2015 18:11:00 -0700
> Jim Meyering <jim <at> meyering.net> wrote:
>
>> [resending, to @debbugs.gnu.org, not @bugs.gnu.org]
>>
>> Thank you Ethan for the report, and Norihiro for the patch.
>> I've made adjustments to the patch, primarily to use the
>> init.sh-based style of test case (permitting to add just one
>> file for each test case, rather than 3 or more) and rewriting
>> the commit log text and NEWS entry.
>>
>> Norihiro, please sanity-check before I push this.
>
> Thanks for review and ajustment.  I confirmed them, and found no missing.
> The test also does work expectedly.

Thanks. Pushed.

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From: Ethan Kaufman <ethan.kaufman <at> gmail.com>
To: bug-sed <at> gnu.org
Subject: deleting lines of a file with sed - unexpected behaviour
Date: Wed, 18 Feb 2015 19:56:58 -0500

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To whom it may concern,

I noticed something odd while fooling around with sed.  If you try to
remove multiple line intervals (by number) from a file, but any interval
specified later in the list is a subset of an interval earlier in the list,
then an additional single line is removed after the specified (larger)
interval.

seq 10 > foo.txt

sed '2,7d;3,6d' foo.txt
1
9
10

Expected output is:

1
8
9
10

Additional tests:

For each additional redundant interval, another line is removed:
sed '2,7d;3,6d;4,5d' foo.txt
1
10

Reversing the order of the intervals produces the expected result!
sed '3,6d;2,7d' foo.txt
1
8
9
10

Specifying the intervals with '-e' produces the same result:
sed -e '2,7d' -e '3,6d' foo.txt
1
9
10

Using different interval syntax has mixed results:
sed -e '/2/,/7/d' -e '/3/,/6/d' foo.txt
1
8
9
10
sed -e '2,7d' -e '/3/,/6/d' foo.txt
1
8
9
10
sed -e '/2/,/7/d' -e '3,6d' foo.txt
1
9
10

Trailing list must be a subset for the additional line to be removed:

sed '2,5d;1,5d'
1
8
9
10
sed '2,5d;2,6d'
1
8
9
10
sed '2,5d;2,5d'
1
9
10

Versions:

Breakage appears to have occurred in the 4.1 release.  See the expected
output for all cases in GNU sed 3.02 and 4.09 (as well as BSD sed (Mac OS X
10.2 Yosemite and /bin/sed on Solaris), but not in 4.15 and 4.21.

This issue and above information has been discussed on stack overflow:
stackoverflow.com/questions/28595574/deleting-lines-of-a-file-with-sed-unexpected-behaviour

Cheers,
Ethan

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