Messages in this thread | | | Date | Wed, 23 Jul 2003 15:28:52 -0400 (EDT) | From | David Korn <> | Subject | Re: Re: kernel bug in socketpair() |
| |
cc: gsf@research.att.com dgk@research.att.com linux-kernel@vger.kernel.org netdev@oss.sgi.com Subject: Re: Re: kernel bug in socketpair() --------
> I missed the reason why you can't use pipes and bash > is able to, what is it? > > If it's the fchown() thing, why doesn't bash have this issue? > >
The reason is that we want to be able to peek ahead at data in the pipe before advancing. You can do this with recv() but this doesn't work wtih pipes. On some systems you can use an ioctl() for this with pipes by Linux doesn't support this so ksh configures to use socketpair() instead of pipe() on Linux. Without the ability to peek ahead on pipes, a command like cat file | { head -6 > /dev/null; cat ;} to remove the first 6 lines of a file would be hard to implement unless head reads one byte at a time from the pipe. (OK, you could read 6 bytes at first if you want to optimize head.)
David Korn dgk@research.att.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |