non-block reading from pipe stdout

[kdevel]

On Tuesday, 3 October 2017 at 00:22:28 UTC, Oleg B wrote:
> but get error "Resource temporarily unavailable".

You get EAGAIN because there is no data available at the time of 
reading.

 From the manpage of read:

ERRORS
        EAGAIN Non-blocking  I/O has been selected using 
O_NONBLOCK and no data
               was immediately available for reading.