What happens when you try to unlink a file being locked?
Let's see...

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(1) Open two terminals.

(2) Execute "php lock-and-sleep.php" in a terminal and
	Execute "php unlink-it.php" in another terminal

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unlink() simply deletes a locked file just like
file_get_contents() reads a locked file.
file_put_contents() also write locked file.
file_put_contents(..,..,,LOCK_EX) is the only one that
waits for the file to be unlocked.

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OK, so unlink() won't wait, and that's fine.
But what happens to the script(a) what opens and locks
a file? when unlink() was done by another script(b),
can the script(a) get the content of the file?