linux-kernel - Re: [PATCH 1/2] perf tools: Setup pager when printing usage and help

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Message-ID: <20151022144101.GE2455@kernel.org>
Date:	Thu, 22 Oct 2015 11:41:01 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Borislav Petkov <bp@...e.de>,
	Brendan Gregg <brendan.d.gregg@...il.com>,
	Chandler Carruth <chandlerc@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Wang Nan <wangnan0@...wei.com>
Subject: Re: [PATCH 1/2] perf tools: Setup pager when printing usage and help

Em Thu, Oct 22, 2015 at 11:28:31PM +0900, Namhyung Kim escreveu:
> It's annoying to see error or help message when command has many options
> like in perf record, report or top.  So setup pager when print parser
> error or help message - it should be OK since no UI is enabled at the
> parsing time.  The usage_with_options() already disables it by calling
> exit_browser() anyway.

But then we don't know what went wrong, try:

[acme@zoo linux]$ perf record --all-cpus -g --42 --event cycles 2>&1 | head
  Error: unknown option `42'

 Usage: perf record [<options>] [<command>]
    or: perf record [<options>] -- <command> [<options>]

    -e, --event <event>   event selector. use 'perf list' to list
available events
        --filter <filter>
                          event filter
        --exclude-perf    don't record events from perf itself
    -p, --pid <pid>       record events on existing process id
[acme@zoo linux]$

Without this patch I can see what was the option that caused the problem
(--42 in this case), after the patch I can see only the valid options,
not the one causing the problem, well, I can see it only if I use the
same 2>&1 technique above.

- Arnaldo
 
> Cc: Adrian Hunter <adrian.hunter@...el.com>
> Cc: Borislav Petkov <bp@...e.de>
> Cc: Brendan Gregg <brendan.d.gregg@...il.com>
> Cc: Chandler Carruth <chandlerc@...il.com>
> Cc: Frederic Weisbecker <fweisbec@...il.com>
> Cc: Stephane Eranian <eranian@...gle.com>
> Cc: Wang Nan <wangnan0@...wei.com>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  tools/perf/util/parse-options.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/perf/util/parse-options.c b/tools/perf/util/parse-options.c
> index 8aa7922397a9..388d385df5ad 100644
> --- a/tools/perf/util/parse-options.c
> +++ b/tools/perf/util/parse-options.c
> @@ -648,6 +648,8 @@ int usage_with_options_internal(const char * const *usagestr,
>  	if (!usagestr)
>  		return PARSE_OPT_HELP;
>  
> +	setup_pager();
> +
>  	fprintf(stderr, "\n Usage: %s\n", *usagestr++);
>  	while (*usagestr && **usagestr)
>  		fprintf(stderr, "    or: %s\n", *usagestr++);
> -- 
> 2.6.0
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