Redirecting pipes?

[Eric S. Raymond]

I've run into a problem with a wrapper shellscript (xmlto, used for
driving the DocBook toolchain) that requires me to filter error
messages set to standard error without disturbing or redirecting 
standard output.

What I need is to be able to write something like this:

tmpfile=/tmp/56tred3a23.xml
xsltproc $tmpfile 2| sed -e ":$tmpfile:s::foobar.xml:"

where "2|" redirects the standard error of the xsltproc command.

Is there a way to do this that does not involve beffering the error
messages in a tempfile?   I need to parae them as they're generated.

I read the documentation, looked at the source code, and don't see 
a way to do this.  If there is not, please consider yhis a feature request.
-- 
                <a href="http://www.tuxedo.org/~esr/";>Eric S. Raymond</a>