What is the best way to ensure only one instance of a Bash script is running? [duplicate]

What is the best way to ensure only one instance of a Bash script is running? [duplicate]

linux bash pid flock lockfile

bash

bash flock: Why 200?

bash flock

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bash flock: exit if can't acquire lock

bash concurrency flock

bash

How do I use the linux flock command to prevent another root process from deleting a file?

linux bash file-locking flock

bash