Re: [PATCH 2/2] shellcheck: suppress SC2327,2328 false positives

[Andrew Jones <andrew.jones@linux.dev>]

On Mon, Sep 08, 2025 at 11:06:18AM +1000, Nicholas Piggin wrote:
> Shellcheck warnings SC2327,SC2328 complain that a command substitution
> will be empty if the output is redirected, which is a valid warning but
> shellcheck is not smart enough to see when output is redirected into a
> command that outputs what the command substitution wanted.
> 
> Add comments and shellcheck directives to these cases.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>  scripts/arch-run.bash | 9 +++++++++
>  scripts/runtime.bash  | 6 ++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/scripts/arch-run.bash b/scripts/arch-run.bash
> index 58e4f93f..9c089f88 100644
> --- a/scripts/arch-run.bash
> +++ b/scripts/arch-run.bash
> @@ -9,6 +9,11 @@ run_test ()
>  
>  	# stdout to {stdout}, stderr to $errors and stderr
>  	exec {stdout}>&1
> +	# SC complains that redirection without tee takes output way from

s/way/away/

Same comment for the other uses below.

> +	# command substitution, but that is what we want here (stderr output
> +	# does go to command substitution because tee is used, but stdout does
> +	# not).
> +	# shellcheck disable=SC2327,SC2328
>  	errors=$("${@}" $INITRD </dev/null 2> >(tee /dev/stderr) > /dev/fd/$stdout)
>  	ret=$?
>  	exec {stdout}>&-
> @@ -23,6 +28,10 @@ run_test_status ()
>  	local stdout ret
>  
>  	exec {stdout}>&1
> +	# SC complains that redirection without tee takes output way from
> +	# command substitution, but that is what we want here (tee is used
> +	# inside the parenthesis).
> +	# shellcheck disable=SC2327,SC2328
>  	lines=$(run_test "$@" > >(tee /dev/fd/$stdout))
>  	ret=$?
>  	exec {stdout}>&-
> diff --git a/scripts/runtime.bash b/scripts/runtime.bash
> index 289e52bb..12ac0f38 100644
> --- a/scripts/runtime.bash
> +++ b/scripts/runtime.bash
> @@ -190,6 +190,12 @@ function run()
>      # qemu_params/extra_params in the config file may contain backticks that
>      # need to be expanded, so use eval to start qemu.  Use "> >(foo)" instead of
>      # a pipe to preserve the exit status.
> +    #
> +    # SC complains that redirection without tee takes output way from command
> +    # substitution, but that is what we want here (tee is used inside the
> +    # parenthesis and output piped to extract_summary which is captured by
> +    # command substitution).
> +    # shellcheck disable=SC2327,SC2328
>      summary=$(eval "$cmdline" 2> >(RUNTIME_log_stderr $testname) \
>                               > >(tee >(RUNTIME_log_stdout $testname $kernel) | extract_summary))
>      ret=$?
> -- 
> 2.51.0

Changed way to away while merging.

Thanks,
drew

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