does php lock files while writing?

[Anon]

I have several php's running that should write to the same logfile.
Does anyone know whether php locks files while writing to them (i'm using fwrite...)?
If not, how is it done in a way that no log-entries are lost?

Thanks Pat

[Anon]

AFAIK, no it doesn't.
However, I have never lost a post from my chat engine and I don't use file locking there. There are frequently several people chatting at once.
(see www.phpbuilder.com/columns/mhall20000621.php3)

/Mike

[Anon]

Hmm, maybe it's time to RTFS. Of course, that didn't help me any when I had my problem with strip_tags()... If the underlying implementation resolves to a call to write(), I think in most unixes these are atomic, but I'm not sure if there is any way of handling the current-location issue (i.e. two or more processes seek to the end of the file, process A writes something that starts at offset 400, now process be writes something to the same location.)

You could always implement a semaphore; someone was asking about those here the other day.