+$lockfn = "$root/local/cluster.lck"; # lock file name
+if (-e $lockfn) {
+ open(CLLOCK, "$lockfn") or die "Can't open Lockfile ($lockfn) $!";
+ my $pid = <CLLOCK>;
+ chomp $pid;
+ die "Sorry, Lockfile ($lockfn) and process $pid exist, a cluster is running\n" if kill 0, $pid;
+ close CLLOCK;
+}
+