The kernel (file system) in Debian supports replacing files even while they're being used.

[Shaul Karl <shaulka@bezeqint.net>]

  Quoting 
http://www.debian.org/doc/FAQ/ch-pkgtools.en.html#s-updaterunning:


    7.2 Debian claims to be able to update a running program; how is this
    accomplished?

    The kernel (file system) in Debian GNU/Linux systems supports replacing
    files even while they're being used.

    We also provide a program called start-stop-daemon which ...


  Does that means that the following sequence should work:

    /tmp$ cp -v /bin/sleep mysleep 
    /tmp$ (./mysleep 100 &); cp -v /bin/sleep mysleep 

? I have a kernel compiled from the kernel-source deb. Yet the above
sequence fails:

    /tmp$ cp -v /bin/sleep mysleep 
    `/bin/sleep' -> `mysleep'
    /tmp$ ./mysleep 100 &
    [4] 4618
    /tmp$ cp -v /bin/sleep mysleep 
    `/bin/sleep' -> `mysleep'
    cp: cannot create regular file `mysleep': Text file busy
    /tmp$

Will that succeeds if I will install a kernel-image deb? If yes, what
is the patch and why it isn't included in the kernel-source deb? If
not, what does it mean that the _kernel (file system)_ in Debian 
supports replacing files even while they're being used?
-- 

    Shaul Karl, shaulka@bezeqint.n e t