display gnome notification-area thing whenever rsync is running

rsync-wait.sh

#!/bin/bash

function in_progress() {
    notify-send "Backup running" "The backup is running.  Please don't unplug Fred";
};

#PID=/tmp/hello/rsnapshot-running
#POLL=10 
GROUP=users # could make this plugdev or staff or whoever
POLL=120
PID=/var/run/rsnapshot.pid

if ! ( id -a | grep -q $GROUP ) ; then
    echo "Not a member of the $GROUP group, exiting" >&2 
    exit 0
fi

if [ x$DISPLAY = x ] ; then
    echo "DISPLAY unset, exiting" >&2
fi

while xset q >/dev/null ; do
    until test -f $PID ; do inotifywait `dirname $PID` 2>/dev/null ;done
    xset q >/dev/null || exit 0
    in_progress
    while test -f $PID ;do
        if zenity --notification --text "Backup in progress" --window-icon=/usr/share/icons/gnome/48x48/actions/document-save.png --timeout $POLL ;then
                 # zenity returns true if the icon is clicked, show a message.
            test -f $PID && in_progress
        fi
    done
    notify-send -t 10000 "Backup finished" "The backup has finished.  It is safe to unplug Fred now"
done

Requires inotify-tools

The xset q calls are probably not as necessary as I thought they were when I added them, but are supposed to make the script die when DISPLAY goes away