x11 forward

# in your ~/.bashrc, add the following

# -- Improved X11 forwarding through GNU Screen (or tmux).
# If not in screen or tmux, update the DISPLAY cache.
# If we are, update the value of DISPLAY to be that in the cache.
function update-x11-forwarding
{
    if [ -z "$STY" -a -z "$TMUX" ]; then
        echo $DISPLAY > ~/.tmux.display.txt
    else
        export DISPLAY=`cat ~/.tmux.display.txt`
    fi
}

# This is run before every command.
preexec() {
    # Don't cause a preexec for PROMPT_COMMAND.
    # Beware!  This fails if PROMPT_COMMAND is a string containing more than one command.
    [ "$BASH_COMMAND" = "$PROMPT_COMMAND" ] && return

    update-x11-forwarding

    # Debugging.
    #echo DISPLAY = $DISPLAY, tmux.display.txt = `cat ~/.tmux.display.txt`, STY = $STY, TMUX = $TMUX
}
trap 'preexec' DEBUG