How might I resolve the fact that the presence of these lines at the bottom
of my .zshenv on a (NetBSD) ISP account


#--------------------------------------------------------------------
# Make sure ssh-agent dies on logout:
trap '
  test -n "SSH_AGENT_PID"  && eval `ssh-agent -k`
' 0

# If no agent is running and we have a terminal, run ssh-agent and ssh-add:
if [ "$SSH_AUTH_SOCK" = "" ]
then
  eval `ssh-agent`
  /usr/bin/tty > /dev/null && ssh-add
fi
#------------------------------------------------------------------


are causing me to be unable to transfer files between that account and my
home Ubuntu box using (either from my home box or from the other side)
rsync or scp?

I need to be able to create and kill ssh-agent as per the .zshenv entry
above.  (This was some recommended stuff from, I think, the O'Reilly
book on SSH.)

But I also need to use scp and rsync to move files and do backups and so
on.

How can I make the lines above work for me without crippling my scp and rsync
functions?