Use a RUNNING file to avoid multiple instances running in the same directory
One must not run two ALF.out instances in the same directory as this will inevitably produce corrupted and likely unrecoverable data files. An easy safeguard is to create a file, say called RUNNING, and delete it only after successful job completion. If the file already exists, ALF refuses to run. This also prevents a re-execution of ALF in a directory where the previous simulation crashed. This is helpful since a crashed run typically requires manual investigation and cleanup. Now the cleanup will have to include removing the file called RUNNING.