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Shared locks are there to protect files from being updated whilst you read them. A shared lock is a signal to the operating system which means "don't let any other process take an exclusive lock on this file as it might change the data I'm reading in mid-read".

A file can have any number of shared (read) locks at any given time. But the operating system will only give an exclusive (write) lock if there are no other locks (of any type) currently on the file.

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<http://www.dave.org.uk>

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In reply to Re: The necessity of flock-ing files that are only to be read. by davorg
in thread The necessity of flock-ing files that are only to be read. by Nemp

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