# See if I am already running
# $my_name was derived earlier from $0
# $pidfile is set up in the scripts headers
if (-f $pidfile) {
    open PID, $pidfile;
    my $pid = <PID>;
    close PID;
    print "read pid $pid\n" if $debug;
    open PROCS, "ps -ef |";
    <PROCS>;    # loose the header
    while (<PROCS>) {
        (undef, my $this_pid) = split;
        if ($this_pid == $pid) {
            print "pid in use $_\n";
            # check this realy is us, not pid re-use by OS
            last unless /$my_name/;
            die "looks like an instance is already running, exiting\n";
        }
    }
}
open PID, ">$pidfile";
print PID $$;
close PID;