passing environment variables back to shell

[Matt Price <matt.price@utoronto.ca>]

Hi,

anyone know if it's possible to pass the value of variables assigned
within a bash script back out to the executing shell?  Or better yet,
to all subsequent shells?

I've written a tiny script to figure out the IP address of my
(dynamically assigned) home computer and pass it to ipmasq on my work
computer.  I would like to run this as a cron job (probably daily,
since my IP is pretty stable) and only rerun ipmasq if the new IP
address differs from the old one.  But I don't understand howto pass
the new value back out to the executing environment.

I think if you look at the script you'll see what I'm trying to do... 

/usr/local/scripts/gethomeip :
-------------------------------------------
#!/bin/bash
HOSTRESULT=`host youknowwho.dyndns.org`
RESULTIP=`echo ${HOSTRESULT##[^0-9]*[^0-9\.]}`

# check the initial values
echo "$RESULTIP"
echo "$MATTSIP"
if [ "$RESULTIP" = "$MATTSIP" ]
 then
echo "no problem, the address is up to date"
else

#set the new value 
MATTSIP=$RESULTIP
echo "$MATTSIP"

# export -- but of course it only exports to daughter processes, not parent processes
export MATTSIP
ipmasq
fi

# check to make sure the variables been set within the script
echo "$MATTSIP"

-----------------------------------------------

obviously export isn't what I'm looking for.  Any ideas what I ought
to substitute there?  thanks,

matt