On Mon, 6 Sep 1999, Alex Povolotsky wrote:

> Hello!
> 
> The following program
> 
> #include <stdio.h>
> #include <fcntl.h>
> 
> main() {
>       int control;
>       if ((control = open("STATUS",O_WRONLY|O_NONBLOCK))<0) {
>               perror("Could not open STATUS ");
>               exit(1);
>       }
>       printf("STATUS ready\n");
>       close(control);
>       return(0);
> }
> 
> fails to run (STATUS is pre-created FIFO file) with error "Device not
> configured", which seems kinda odd for me.
> 
> However, when FIFO is opened with O_RDWR and O_NONBLOCK, every attempt 
> to select(2) its handler for writing doesn't wait until someone opens
> FIFO for reading, but instead FIFO is ready to write at every select.
> 
> Is it a bug or a feature?
> 

I answered a similar question some time ago.  You can search the mailing
list archive for this.  Basically, you need to read the "Advanced Unix
Programming Environment" by Stevens.  I can not remember every details
right now.  The "device not configured" error is expected. 

-Zhihui



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