The pipe utility is for piping between files using the
semantics of POSIX stdio.

An example of piping clock jitter to a terminal session:

! <start name="pipe">
!   <resource name="RAM" quantum="2M"/>
!   <config>
!     <vfs>
!       <jitterentropy name="rng"/>
!       <terminal name="tty"/>
!     </vfs>
!     <libc stdin="/rng" stdout="/tty"/>
!   </config>
! </start>