exec | wc isn't very useful...

[Anthony Heading <aheading@jpmorgan.com>]

Hi,

Can anyone tell me why this doesn't do what I'd hope:

    exec | wc

I'm wondering how to redirect the shell's "default" stdout into
a process, e.g. do the equivalent of perl's

    open(STDOUT, "| wc");
    print "two words";

Obviously one can do "echo two words | wc", or "wc <(echo two words)"
or whatever, but that doesn't seem to lend itself too well to
conditional redirection, viz:

    case $out in
	script)  exec > script.out ;;
	gnuplot) exec | gnuplot ;;  # doesn't work - hmm
	stdout) ;;
    esac

Equivalently, a sometimes appealing alternative to:

    (
	echo foo
	echo bar
    ) > xyzzy.txt

is

    exec > xyzzy.txt
    echo foo
    echo bar

but this doesn't seem to work for pipelines.  Except that
perl can do it no trouble...

Pointers to anything I'm missing very welcome...

Rgds

Anthony

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