On Thu, Jan 31 2008, WANG Cong wrote: > On Thu, Jan 31, 2008 at 02:28:58PM +0100, Jens Axboe wrote: > >On Thu, Jan 31 2008, Michael Kerrisk wrote: > >> > >> > >> 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. > > > I think man page should mention about this usage. Hmm, but it does - you even quoted the EINVAL return documentation yourself. The description mentions that it dupes between the pipes referred to by fd_in and fd_out. Not sure how much else we can do there? > >> 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? > > > >See ktee.c from the splice sample repo, it works correctly: > > > >axboe@carl:~/git/splice> echo hello | ./ktee outfile | cat > >hello > >axboe@carl:~/git/splice> cat outfile > >hello > > > >I don't have the tee(2) man page here so can't verify, but try and > >compare them! > > > > I have the same problem here with what Michael mentioned. > But my output file is *not* empty. Shown below: > > $ echo hello | ./tee fooo.txt | cat > hello > <=== here blocked, type ctrl+c, exit > $ cat fooo.txt > hello > > My kernel version is 2.6.21-1.3194.fc7. I don't know what 'tee' is - is it the one from the man page, or the one from my splice tools? -- Jens Axboe - To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
