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A simple question. Do scripts that try to read a file locked with file_put_contents that uses LOCK_EX wait until the file is unlocked or fail reading and continue?

Desmond Hume
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  • @chiliNUT I would need a huge file to try it, or wouldn't I? – Desmond Hume Nov 30 '13 at 19:49
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    possible duplicate of [How can I use file\_put\_contents() with FILE\_APPEND | LOCK\_EX safety?](http://stackoverflow.com/questions/9009058/how-can-i-use-file-put-contents-with-file-append-lock-ex-safety) – mario Nov 30 '13 at 19:49
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    `dd if=/dev/zero of=output.dat bs=1M count=10` creates a 1M x 10 = 10MB file, make a file as big as you need and use that – chiliNUT Nov 30 '13 at 19:51
  • @mario The author of the accepted answer says `So since file_get_contents() utilizes it [flock()], I'd assume it's the same`. It's an assumption, and even if it does use `flock()`, he doesn't really know for sure whether it uses `LOCK_NB` or not (left alone he's talking about `file_get_contents` for whatever reason while my question concerns locking files with `file_put_contents` and reading of such files in general). – Desmond Hume Nov 30 '13 at 20:02
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    There's a more detailed answer in [should LOCK\_EX on both read & write be atomic?](http://stackoverflow.com/q/4899737). It's still not an authoritative answer (but I'd rather see new answers added there instead of a new duplicate). Btw, it's at least supposed *to wait*, regardless of the underlying implementation. – mario Nov 30 '13 at 20:07

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From the file_put_contents man page, here

This function returns the number of bytes that were written to the file, or FALSE on failure.

...so, this would happen immediately after the script is run.

Groovepig
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