Single Instance

[jsau]

I have a rapidly changing filesystem and on detecting filesystem changes FFS runs multiple times (too many times if left unattended and crashes - the other instances wait for the current lock to finish, but the lock file takes some time to appear :(....esp on a network!) - is there any way to ensure FFS is only running one instance at a time? ie if already running, it wont start up another instance? Or to ensure sync is accurate (start sync may take some time, so may not be the same as the next sync, etc.), only run 2 instances max? or perhaps have an X maximum instances allowed (GUI/command line option?) feature?