'who' is your best bet, although the syntax you want is going to depend on your OS to some degree. i don't know what you'd be using netstat for. here's a chunk of code i use to get IP's under solaris and tru64/OSF1

OS=`uname`

if [ "$OS" = "SunOS" ]; then
        IP=`who am i | cut -f 2 -d \( | cut -f 1 -d \)`
elif [ "$OS" = "OSF1"]; then
        IP=`who -M am i | cut  -f 2 -d \( | cut -f 1 -d \)`
fi
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