linux-kernel - Re: [PATCH] selftests/cpufreq: Fix cpufreq basic read and update testcases

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Message-ID: <20250522094520.22zwevl6vgrjf3aw@vireshk-i7>
Date: Thu, 22 May 2025 15:15:20 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: "Sapkal, Swapnil" <swapnil.sapkal@....com>
Cc: rafael@...nel.org, shuah@...nel.org, gautham.shenoy@....com,
	narasimhan.v@....com, linux-pm@...r.kernel.org,
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] selftests/cpufreq: Fix cpufreq basic read and update
 testcases

On 22-05-25, 14:07, Sapkal, Swapnil wrote:
> Initially I tried the same, but it does not work properly with the root user.

Hmm,

Tried chatgpt now and it says this should work:

if ! cat "$1/$file" 2>/dev/null; then
    printf "$file is not readable\n"
fi

- This attempts to read the file.
- If it fails, the cat command returns non-zero, and you print a message.
- 2>/dev/null suppresses error messages (Permission denied, etc.)
- This works reliably for both root and non-root users, because it actually tests the read action, not just permission bits.

-- 
viresh