Well, it's never necessary to use die after an open. You ought to check the return value of open, and do something appropriate if it fails. For many programs, a die is appropriate.

Having said that, a flock is just a flock. Most systems don't have manditory locks, and a flock on a file does not prevent it to be opened. In fact, a flock on the file doesn't prevent it to be read, or written to. Multiple processes accessing a file do have to cooperate using flock, but if a process decides not to, you are out of luck.

How systems work that have manditory file locking, with respect to open, I do not know.

Abigail