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Date:   Wed, 24 Jun 2020 23:16:03 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Naresh Kamboju <naresh.kamboju@linaro.org>
Cc:     Michael Ellerman <mpe@ellerman.id.au>,
        Joe Lawrence <joe.lawrence@redhat.com>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        Anders Roxell <anders.roxell@linaro.org>,
        Daniel =?iso-8859-1?Q?D=EDaz?= <daniel.diaz@linaro.org>,
        Justin Cook <justin.cook@linaro.org>,
        lkft-triage@lists.linaro.org, Miroslav Benes <mbenes@suse.cz>,
        Petr Mladek <pmladek@suse.com>, Shuah Khan <shuah@kernel.org>
Subject: Re: [PATCH 1/2] selftests/lkdtm: Don't clear dmesg when running tests
Message-ID: <202006242312.8888AAFE@keescook>
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 <CA+G9fYtHP+Gg+BrR_GkBMxu2oOi-_e9pATtpb6TVRswv1G1r1Q@mail.gmail.com>
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On Mon, Jun 22, 2020 at 02:21:38PM +0530, Naresh Kamboju wrote:
> On Fri, 8 May 2020 at 12:23, Michael Ellerman <mpe@ellerman.id.au> wrote:
> >  # Record and dump the results
> > -dmesg -c >"$LOG"
> > +dmesg | diff --changed-group-format='%>' --unchanged-group-format='' "$DMESG" - > "$LOG" || true
> 
> We are facing problems with the diff `=%>` part of the option.
> This report is from the OpenEmbedded environment.
> We have the same problem from livepatch_testcases.

Does "comm" exists in those environments?

dmesg | comm -13 "$DMESG" - > "$LOG" || true

this is even shorter than the diff command line. :)

-- 
Kees Cook