"epilogue" script?

[Ian Smith]

In freebsd-questions Digest, Vol 608, Issue 6, Message: 20
On Sat, 30 Jan 2016 11:59:55 +0100 Polytropon <freebsd at edvax.de> wrote:
 > On Fri, 29 Jan 2016 16:35:07 -0600 (CST), Valeri Galtsev wrote:
 > > Dear Experts,
 > > 
 > > How does one create "epoligue" script in FreeBSD. By "epoligue" script
 > > script I mean here the script that is executed after everything described
 > > in /etc/rc.conf is done (services started, interfaces initialized etc.). I
[..]

 > a) RC framework: rc.d
   [..]
 > See "man rc" and "man rcorder" for details.

Sure, if installing new daemon processes, this is the way to go.

OTOH, for scripts needing running just once at startup, and/or possibly 
once at shutdown:

 > b) rc.local and rc.shutdown.local
 > 
 > Those files, located in /etc, are "real" shell scripts that will be
 > executed "quite late", but not at the lastest possible point. Here
 > is an example:
 > 
 > 	Creating and/or trimming log files.
 > 	Starting syslogd.
 > 	No core dumps found.
 > 	Additional ABI support: linux.
 > 	Starting named.
 > 	Clearing /tmp (X related).
 > 	Starting local daemons: activity.	<--- /etc/rc.local runnung now!
 > 	Starting ntpd.
 > 	Starting dhcpd.
 > 	Starting cupsd.
 > 	Configuring syscons: keymap keyrate font8x16 font8x14 font8x8.
 > 	Starting sshd.
 > 	Starting cron.
 > 	Starting inetd.
 > 
 > As you can see, there are other services started _after_ rc.local has
 > been run. This might cause a problem for you when you need those services
 > running.

Yes.  I was preparing to post a very similar segment, which also wrote 
something to stdout when /etc/rc.local was sourced - so thanks!

 > See from "man rc":
 > 
 > 	The rc.local script contains commands which are pertinent only
 > 	to a specific site.  Typically, the /usr/local/etc/rc.d/ mechanism
 > 	is used instead of rc.local these days but if you want to use rc.local,
 > 	it is still supported.  In this case, it should source /etc/rc.conf
 > 	and contain additional custom startup code for your system.  The best
 > 	way to handle rc.local, however, is to separate it out into rc.d/
 > 	style scripts and place them under /usr/local/etc/rc.d/. The rc.conf
 > 	file contains the global system configuration information referenced
 > 	by the startup scripts, while rc.conf.local contains the local system
 > 	configuration.  See rc.conf(5) for more information.
 > 
 > So this might not be "stable".

It's stable; been there since the dawn of time and isn't going away :)

Valeri, picking up on the above, if you run, say:

 % rcorder /etc/rc.d/* /usr/local/etc/rc.d/* | less

and find 'local', you'll see where /etc/rc.d/rc/local runs, and that's 
what runs (sources inline) /etc/rc.local on startup (or in reverse order 
on shutdown, /etc/rc.shutdown.local)

You only need source /etc/rc.conf if using rc.conf variables of course.

 > c) /etc/rc hook

Totally agree; don't go anywhere near there :)

 > > I'm left clueless. As Linux refugee I have a feeling that this is doable
 > > without a hack, like making init script, and having "sleep ..." in it
 > > before payload. In Linux this is done using /etc/rc.d/rc.local which is
 > > executed _after_ everything else is done.
 > 
 > As you can see, an rc.d style mechanism will probably be the best
 > solution here, except you are fully sure that the time when rc.local
 > is run you will be provided with everything you need.

We don't really know what Valeri wants to run, and whether it's one or 
more daemons, maybe including long-running background scripts, that may 
need start|stop|status control via service(8), or whether it's more 
simply one or more one-off tasks to be run sometime after startup?

If the latter, there's nothing at all wrong with starting a script that 
runs in the background including sleep(1), so long as you don't have an 
inline sleep that would just pause the whole startup.  Something like ..

/etc/rc.local:	(do not use exit or return, this runs within /etc/rc)
wait=20
( sleep $wait	# sleep 5 should usually be more than enough
  # perhaps wait for something or other to be running or exist?
  # do stuff, maybe including starting further bg jobs, whatever ..
) &
echo "my rc.local stuff starts in $wait seconds"

cheers, Ian