Re: Question about memory-mapped files

[John M Collins (jmc@xisl.com)]

Hugh Dickins wrote:

> On Wed, 28 May 2003, John M Collins wrote:
>  
>
> > If I invoke mmap to map a file to memory, and it succeeds, can I safely 
> > close the original file descriptor and rely on the memory still being 
> > mapped and the file still updated (possibly with mysnc)?
> >    
>
> Yes, that's definitely a part of the specification of mmap,
> even if it's not mentioned on the man page.
>
> Note that the file on disk is likely not to be updated until
> some time after you unmap it, unless you use msync to force it.
Thanks - FYI the file mod time eventually got updated on HP-UX but not 
on Solaris (2.9) or Linux (2.4.21) - and it doesn't seem to update it 
even if you don't close the f.d. I think that has to be wrong if the 
manual page is anything to go by.

--
John Collins Xi Software Ltd www.xisl.com



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