How should command substitution (`...`) work?

[Doug Gwyn <gwyn>]

> 		p `egrep -l pattern *`
>
>      It seems more natural to me that the shell should (silently) not
> run a pipeline if any command substitutions in it fail.

The Bourne shell "never" fails on a file pattern; if there is no match
it just uses the pattern itself.  There was at one time a shell variable
called FILEMATCH that one could set to obtain a different behavior, but
there was not much enthusiasm for this so it went away.