processing of pipelines

[Sweth Chandramouli <sweth@xxxxxxx>]

	i've been part of a recent discussion in the comp.unix.shell
newsgroup about how different shells process pipelines, and thought i 
should ask this group about zsh's behaviour.  some quick tests first 
led me to believe that zsh runs each command in a pipeline
sequentially in the current process; some more research now makes me 
think that this only appeared to be the case because i was testing
using a no-op on one side of the pipe, and zsh somehow checks to see 
if the command on the right side of a pipe is actually reading from
the pipe; if not, it treats the pipe like a semicolon.
	my new hypothesis, then, is that zsh (like ksh) runs all commands
in a pipeline in sub-processes except for the last command, which is
run in the current process, but that when the pipe isn't actually
being used, it splits the pipeline up into smaller lists to be
processed individually.  yes?  no?  something else entirely?

	-- sweth.

-- 
Sweth Chandramouli ; <sweth@xxxxxxx>
<a href="http://astaroth.nit.gwu.edu/resume/";>Will Work For Food.</a>
<a href="http://astaroth.nit.gwu.edu/~sweth/disc.html";>*</a>