Hello Patrick On 09/24/2016 12:17 AM, Patrick McLean wrote: > The FIONREAD ioctl can be used on a pipe to get the current amount of > data in the pipe. This ioctl is currently only documented in tty_ioctl > (4). This adds a blurb to the pipe(7) man page about this ioctl. Thanks for the patch. In the end, I wrote something more extensive. See below. Cheers, Michael diff --git a/man7/pipe.7 b/man7/pipe.7 index 9977acc..b6a3007 100644 --- a/man7/pipe.7 +++ b/man7/pipe.7 @@ -143,6 +143,21 @@ operations. See .BR fcntl (2) for more information. + +The following +.BR ioctl (2) +operation, which can be applied to a file descriptor +that refers to either end of a pipe, +places a count of the number of unread bytes in the pipe in the +.I int +buffer pointed to by the final argument of the call: + + ioctl(fd, FIONREAD, &nbytes); + +The +.B FIONREAD +operation is not specified in any standard, +but is provided on many implementations. -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- 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
