alt Hacker Newsthis is great thanks,
was just wondering, could something else remove the dir in between the if and then, before trap?
Just wondering about the atomicity.
Replies
cryptonector • yesterday at 9:30 PM
The problem with lock files and lock directories is that if the lock holder dies without cleaning up you now need to do something to clean up.
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formerly_proven • yesterday at 7:09 PM
Yes, but that is not a weakness in the locking.
The permissions on the parent and lock directory could restrict the access to a specific user and group, but yes, other processes could interfere with this locking if directed to do so.
One condition where this interference is helpful is a crash, where a @reboot entry in the crontab could:
You would also not want to place the lock directory in /tmp or otherwise where other users could manipulate (or see) it. In Red Hat, there is a /var/run/lock directory that might be appropriate.My biggest use case for directory locking in scripts is handling inotify events.