Re: [PATCH v2] selftests: splice: Add usage() to splice_read.c

[Shuah Khan]

On 8/30/24 23:14, Rong Tao wrote:
> From: Rong Tao <rongtao@xxxxxxxx>
>
> Give the programmer more help information to inform the program on how to
> use it.
>
> Signed-off-by: Rong Tao <rongtao@xxxxxxxx>
> ---
>   tools/testing/selftests/splice/splice_read.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/splice/splice_read.c b/tools/testing/selftests/splice/splice_read.c
> index 46dae6a25cfb..73a8bc146f97 100644
> --- a/tools/testing/selftests/splice/splice_read.c
> +++ b/tools/testing/selftests/splice/splice_read.c
> @@ -9,6 +9,12 @@
>   #include <sys/types.h>
>   #include <sys/stat.h>
>   
> +void usage(const char *prog)
> +{
> +	fprintf(stderr, "Usage: %s INPUT [BYTES]\n", prog);
> +	fprintf(stderr, "       %s /etc/os-release | cat\n", prog);

How does replacing %s INPUT [BYTES]\n", prog with /etc/os-release | cat\n" do?
Also what happens on distros that don't have os-release file?

> +}
> +
>   int main(int argc, char *argv[])
>   {
>   	int fd;
> @@ -16,7 +22,7 @@ int main(int argc, char *argv[])
>   	ssize_t spliced;
>   
>   	if (argc < 2) {
> -		fprintf(stderr, "Usage: %s INPUT [BYTES]\n", argv[0]);
> +		usage(argv[0]);
>   		return EXIT_FAILURE;
>   	}
>   
> @@ -49,6 +55,7 @@ int main(int argc, char *argv[])
>   		      size, SPLICE_F_MOVE);
>   	if (spliced < 0) {
>   		perror("splice");
> +		usage(argv[0]);
>   		return EXIT_FAILURE;
>   	}
>   

I don't understand how this change helps user.

thanks,
-- Shuah