Published at LXer:
This isn't about a shell script, it's about a really cool technique to apply in shell scripts. Have you ever been worried about multiple instances of a shell script running because they might overwrite or corrupt the data or devices they are working on? Here's a way to prevent that. There's a Unix system call named flock(2). It's used to apply advisory locks to open files. Without exhausting the subject, it can be used to synchronize access to resources across multiple running processes.
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