Re: open for append

I learned that the POSIX C library guarantees that, when multiple processes are writing to the same file, and all of them have the file opened for appending, data shall not be lost.

But I don't think that guarantees that data won't be interleaved, with output from process A in the middle of a write from process B. Does it?

Comment on Re: open for append

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Re^2: open for append by perrin (Chancellor) on Aug 25, 2005 at 11:10 UTC
It does. It seeks to the end before every write.	[reply]
Re^3: open for append by kscaldef (Pilgrim) on Aug 26, 2005 at 18:20 UTC
Make sure to note merlin's comment below. It's not sufficient to seek then write in userspace, because it's not atomic. It needs to happen in the kernel, not libc.	[reply]