RE: 2.4 and 2GB swap partition limit

David S. Miller
2001-04-30T19:09:14Z

Richard B. Johnson writes:
> On Mon, 30 Apr 2001, Torrey Hoffman wrote:
> > In general, is there a safe way to replace executable files for
> > programs that might be running while their on-disk images are
> > replaced?
>
> Yes. Perfectly safe:
>
> mv /usr/bin/exeimage /usr/bin/exeimage.sav
> cp /wherever/exeimage /usr/bin/exeimage
>
>
> The executing task will continue to use the old image until it exits.

Even more effective is:

mv /wherever/exeimage /usr/bin/exeimage

The kernel keeps around the contents of the old file while
the executing process still runs.

This is also basically how things like libc get installed.
A single mv is not only preserves currently referenced contents,
it is atomic.

Later,
David S. Miller
davem@redhat.com