Isn't that obvious?
When the first redirected stdin gives eof, it switches to the next one.

I've never seriously played with zsh, but I've always been someone 
intrigued by it. I wonder if any other shell have that one.

	Johnny

Hubert Feyrer wrote:
> On Tue, 18 Apr 2006, Chavdar Ivanov wrote:
> 
>> root@loan8>   cat - - - < /tmp/1 < /tmp/2 </tmp/3
>>                                             /tmp
>> 11111
>> 22222
>> 33333
> 
> 
> Wow. How does that work?
> 
> I'm familiar with the concepts of stdio, stdin and eof, but
> how does cat/zsh know when to attach the next file to the stdin file 
> descriptor?
> 
> 
>  - Hubert

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt@update.uu.se           ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol