Re: Generically running rc scripts

[David Brownlee <abs%netbsd.org@localhost>]

On 18 November 2011 11:22, Julian Fagir <gnrp%komkon2.de@localhost> wrote:
>
> Hi,
>
> > > About the former matter: It's good for omitting redundant code
> > > for parsing rc_directories, rcvar and name. If you want to
> > > restart a service currently, you have to parse rc.conf and in
> > > some cases also all rc scripts manually for their names and
> > > rcvar to get the right one.
> >
> > What redundant code would be eliminated, and what manual parsing
> > would be eliminated?  I am just not seeing it.
> >
> > Sure, there are a few lines of redundant code at the top of each
> > rc.d script, but adding a wrapper does nothing to remove that
> > redundant code.  Getting rid of the rc.d scripts would get rid of
> > the redundant code, but I thought you explicitly said that you did
> > not want to do that.
> this is not about changing anything about rc.d scripts, they shall remain in
> place and not be touched. It's just for userland programs to simplify
> restarting things.
>
> > When I want to restart a service like "named", I don't have to do
> > any manual parsing; I just run "/etc/rc.d/named restart".
> This is the easiest case. But say, you have several rc_directories and you
> want to know if a specific additional service is enabled, which does not have
> the same name as its rc variable.
> Then you have to parse rc.conf, check all rc directories, check their rc
> variables, evaluate their rc variables and names and then check back rc.conf
> whether it is enabled.
>
> But, though it might be bad style, there's also the name variable in each rc
> script, still forcing you to check all scripts.
> If there is e.g. no /etc/rc.d/named, you would have to check all files in all
> rc_directories by hand for the name named you're looking for.
> Either a few lines of sh code or one bad-ass line of sed-sh-mix.
>
> Doing any rc magic from a C program must use shell scripts for that, because
> otherwise parsing rc scripts manually in C is too much effort.
>
>
> I know these use cases are very... constructed ones. Perhaps there's only one
> use case (for me), so I'd better pack it together with th eother things I'm
> doing. I just thought it could be a nice addition, maybe only for pkgsrc.

I'd quite like to see this imported into NetBSD, pretty much for the
two obvious reasons:
- rc locations differ between systems (BSD, differing Linuxes), this
allows "service squid restart" across any of them
- The -e option as Julian mentions would be very convenient to provide
a list of effective rc values (from whichever file they are defined).