Re: Man page bugs?

[Michael Kerrisk <mtk.manpages-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>]

Jens Axboe wrote:
> On Thu, Jan 31 2008, Michael Kerrisk wrote:
>> Hi Cong,
>>
>> WANG Cong wrote:
>>> Hi, Michael and list!
>>>
>>> I found two problems in the man pages. The first one should
>>> be a bug. It is that the type of the 2nd and 4th arguments
>>> of splice(2) is wrong. The current prototype of splice(2)
>>> in current man page is:
>>>
>>>        long splice(int fd_in, off_t *off_in, int fd_out,
>>>                    off_t *off_out, size_t len, unsigned int flags);
>>>
>>> However, they should be 'loff_t' instead of 'off_t'. If we
>>> use 'off_t', gcc will generate a warning. Patch is in the end
>>> of this email and it's against 2.76 release. ;)
>> Thanks for spotting that.  Fixed as you suggest, for man-pages-2.77.
>>
>>> The second one is a bit confused. The example given in tee(2)
>>> even can not run normally. I got this error:
>>>
>>> $ ./example bar.txt
>>> tee: Invalid argument
>>>
>>> I looked at tee(2), it is said that:
>>>
>>> EINVAL fd_in  or  fd_out  does not refer to a pipe; or fd_in and fd_out
>>>        refer to the same pipe.
>>>
>>> So the first two arguments of tee(2) in the example is wrong,
>>> since neither STDIN_FILENO nor STDOUT_FILENO refers to a pipe.
>>> But I am not so sure, because I am new to tee(2). ;) If you can
>>> comfirm this is really a bug, I can send a patch to fix this too.
>>>
>>> I have checked the newest release of man pages and my kernel version
>>> is 2.6.21-1.3194.fc7. Did I miss something obvious?
>> I'm not sure.  Perhaps Jens, the implementer of tee(2) can provide a little
>> help.  Jens, what's an example of a command line for running the example
>> program in the tee.2 man page?
> 
> It's not a bug, it should be run as:
> 
> $  echo hello | ./example output_file | cat
> 
> so that both stdin and stdout are pipes, as described in the man page.
> The man page is correct.

Hi jens,

Yes, I guessed you probably should run it like that.  And it does produce
the expected output on stdout.  However, the command then blocks, and if
one types control-C, the output_file is empty.  How should this program be
terminated so that something does end up in the output_file?

Cheers,

Michael

-- 
Michael Kerrisk
Maintainer of the Linux man-pages project
http://www.kernel.org/doc/man-pages/
Want to report a man-pages bug?  Look here:
http://www.kernel.org/doc/man-pages/reporting_bugs.html