[adunsmoor]

What do you mean?

  exec cat /etc/passwd | grep root

works just fine.

You can also use Tcl's open command with a pipe to do back and forth communication with a subprocess.

http://www.tcl.tk/man/tcl/tutorial/Tcl26.html

[jneen]

Yes, tcl's `exec` command implements a special syntax for using UNIX pipes, but what I'm referring to is not UNIX pipes, but a language feature - an interactive language needs to implement some kind of pipe/chain/cascade syntax, so you can use the results of a command without having to go back and surround it with parentheses or brackets.