GNU bug report logs - #33622
coreutils v. 8.30 – Tail prints the first row in 'tail -n <N>'

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Ricky Tigg <ricky.tigg <at> gmail.com>
To: bug-coreutils <at> gnu.org
Subject: coreutils v. 8.30 – Tail prints the first row in 'tail -n <N>'
Date: Wed, 5 Dec 2018 11:51:09 +0100

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

OS: *Fedora*. Component: coreutils.x86_64 8.30-6.fc29 @System

Tail prints the first row in 'tail -n <N>'

Command executed:
$ dnf repoquery --requires bash --recursive --resolve | grep -E
'.x86_64$|.noarch$' | tail -n 1
Last metadata expiration check: 0:28:25 ago on Wed Dec  5 11:09:16 2018.
tzdata-0:2018g-1.fc29.noarch

Expected result: command to only print N rows, which means without printing
the first row.

[Message part 2 (text/html, inline)]

Message #8 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Kamil Dudka <kdudka <at> redhat.com>
To: Ricky Tigg <ricky.tigg <at> gmail.com>
Cc: 33622 <at> debbugs.gnu.org, bug-coreutils <at> gnu.org
Subject: Re: bug#33622: coreutils v. 8.30 – Tail prints the
 first row in 'tail -n <N>'
Date: Wed, 05 Dec 2018 13:49:31 +0100

On Wednesday, December 5, 2018 11:51:09 AM CET Ricky Tigg wrote:
> OS: *Fedora*. Component: coreutils.x86_64 8.30-6.fc29 @System
> 
> Tail prints the first row in 'tail -n <N>'
> 
> Command executed:
> $ dnf repoquery --requires bash --recursive --resolve | grep -E
> '.x86_64$|.noarch$' | tail -n 1
> Last metadata expiration check: 0:28:25 ago on Wed Dec  5 11:09:16 2018.
> tzdata-0:2018g-1.fc29.noarch
> 
> Expected result: command to only print N rows, which means without printing
> the first row.

The line "Last metadata expiration check: [...]" is not printed by tail
at all.  It is printed by dnf to standard _error_ output.  You will see
it even if you redirect dnf's standard output to /dev/null:

$ dnf repoquery --requires bash --recursive --resolve >/dev/null
Last metadata expiration check: [...]

You can use `dnf --quiet ...` to suppress the message.

Message #14 received at 33622 <at> debbugs.gnu.org (full text, mbox):

From: Assaf Gordon <assafgordon <at> gmail.com>
To: Kamil Dudka <kdudka <at> redhat.com>, Ricky Tigg <ricky.tigg <at> gmail.com>
Cc: 33622 <at> debbugs.gnu.org
Subject: Re: bug#33622: coreutils v. 8.30 – Tail prints the first row in 'tail -n <N>'
Date: Sat, 22 Dec 2018 22:46:44 -0700

tags 33622 notabug
close 33622
stop

Hello,

On 2018-12-05 5:49 a.m., Kamil Dudka wrote:
> On Wednesday, December 5, 2018 11:51:09 AM CET Ricky Tigg wrote:
>> OS: *Fedora*. Component: coreutils.x86_64 8.30-6.fc29 @System
>>
>> Tail prints the first row in 'tail -n <N>'
>>
>> Command executed:
>> $ dnf repoquery --requires bash --recursive --resolve | grep -E
>> '.x86_64$|.noarch$' | tail -n 1
>> Last metadata expiration check: 0:28:25 ago on Wed Dec  5 11:09:16 2018.
>> tzdata-0:2018g-1.fc29.noarch
>>
>> Expected result: command to only print N rows, which means without printing
>> the first row.
> 
> The line "Last metadata expiration check: [...]" is not printed by tail
> at all.  It is printed by dnf to standard _error_ output.  You will see
> it even if you redirect dnf's standard output to /dev/null:
> 
> $ dnf repoquery --requires bash --recursive --resolve >/dev/null
> Last metadata expiration check: [...]
> 
> You can use `dnf --quiet ...` to suppress the message.

Thank you Kamil for explaining the issue.

I'm closing this as "notabug".

-assaf

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