linux-kernel - Re: [PATCH] tools: perf: Use "grep -E" instead of "egrep"

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Date:   Mon, 21 Nov 2022 10:58:55 +0800
From:   Tiezhu Yang <yangtiezhu@...ngson.cn>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH] tools: perf: Use "grep -E" instead of "egrep"



On 11/20/2022 02:17 AM, Ian Rogers wrote:
> On Fri, Nov 18, 2022 at 1:17 AM Tiezhu Yang <yangtiezhu@...ngson.cn> wrote:
>>
>> The latest version of grep claims the egrep is now obsolete so the build
>> now contains warnings that look like:
>>         egrep: warning: egrep is obsolescent; using grep -E
>> fix this up by moving the related file to use "grep -E" instead.
>>
>>   sed -i "s/egrep/grep -E/g" `grep egrep -rwl tools/perf`
>>
>> Here are the steps to install the latest grep:
>>
>>   wget http://ftp.gnu.org/gnu/grep/grep-3.8.tar.gz
>>   tar xf grep-3.8.tar.gz
>>   cd grep-3.8 && ./configure && make
>>   sudo make install
>>   export PATH=/usr/local/bin:$PATH
>>
>> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
>
> Hi Tiezhu,
>
> installing a newer grep tool in order to build/test perf is somewhat
> burdensome, as such I don't think we should merge this change. Looking
> at my Debian derived distro. I have grep 3.7, so I'd need to do this.
> I imagine the majority of people are using a grep earlier than 3.8. I
> agree there is a problem perhaps we can:
>  - rewrite to just need grep and not egrep;
>  - rewrite in a stable language with regex support, perhaps python;
>  - have a grep/egrep wrapper that selects based on version number.
>

Hi Ian,

I found this issue on Linux From Scratch system which uses grep 3.8 [0],
we can see the following NEWS in grep-3.8 release announcement [1]:

"The egrep and fgrep commands, which have been deprecated since
  release 2.5.3 (2007), now warn that they are obsolescent and should
  be replaced by grep -E and grep -F."

Additionally, the next grep rpm/deb version is 3.8 on Fedora [2]
and Debian [3], so use "grep -E" instead of "egrep" so we won't see
the warning for various versions of grep.

[0] https://linuxfromscratch.org/~thomas/multilib/chapter06/grep.html
[1] https://savannah.gnu.org/forum/forum.php?forum_id=10227
[2] https://packages.fedoraproject.org/pkgs/grep/grep/fedora-rawhide.html
[3] https://packages.debian.org/sid/grep

Thanks,
Tiezhu