Hi,
The buffer-cache is a kernel-internal datastructure that you do not have to
worry about in applications.
The 'buf' variable in your code is a local buffer, which is not anything
special to the kernel but just another piece of memory.
The next file-read will therefore come from the file, or from the
kernel-internal buffercache which always represents the file on disk.
If you write the new data to disk with the write() statement, the write will
go thru the buffercache, and at some point in future the new
buffercache-data will be written to the actual disk. To all applications,
the fact that on-disk is not identical to buffer-cache is always invisible;
the contents of the buffercache _is_ the contents of the file. There is no
way to get round the kernel for reading this file :-)
The buf[] variable in your code however, is not directly connected to the
kernel's internal buffercache and any modifications that you make to this
application-local piece of memory has no bearing on the file/buffercache
whatsoever until you write() that data :-)
Greetings,
--Tim
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This archive was generated by hypermail 2b29 : Tue Aug 15 2000 - 21:00:24 EST