Set display variable when reconnect to a tmux terminal on a server with many users (display can change on each ssh section)

setdisplay bash function

function setdisplay ()
{
    USERID=$(id -u);
    # list all connections by numeric (don´t wait slow DNS)
    # and filter by current user´s listening ports on localhost
    # that that is in the range of 6000 ~ 6999 (generally X ports)
    PORTA=$(netstat -ane|grep "LISTEN "|grep "$USERID"|sort -k8n|sed -n -e "s/.*127\.0\.0\.1:6.\(..\) .*/\1/p"|tail -n 1);
    export DISPLAY="localhost:$PORTA.0"
}