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 is used
to start daemons at boot time or to stop daemons when the kernel runlevel is
changed (e.g., from multi-user to single-user or to halt). The same program is
used by installation scripts when a new package containing a daemon is
installed, to stop running daemons, and restart them as necessary.