[Buildroot] [PATCH 1/2] modem-manager: fix test of unset variable in init script

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello,

On Sun, 15 Apr 2018 12:31:49 -0300 (BRT), Carlos Santos wrote:

> >> +MODEMMANAGER_BIN=/usr/sbin/ModemManager
> >>  PIDFILE=/var/run/ModemManager.pid
> >>  
> >>  [ -x $MODEMMANAGER_BIN ] || exit 0  
> > 
> > In fact, I think this test doesn't make sense. It just exits without
> > any error if the binary doesn't exists, which is silly.
> > 
> > I'm advocating for removing such tests altogether, which would make the
> > MODEMMANAGER_BIN variable unnecessary.  
> 
> I think the original purpose of these test was allowing the user to
> disable the service by chmod'ing -x the executable file. We discussed
> a similar situation in
> 
>    https://patchwork.ozlabs.org/patch/818897/
> 
> [which by the way is still in my endless to-do list]

Well, if you look at my feedback on this patch, I was already saying
that the test to check whether radvd was executable or not was not
useful.

I don't think making a binary program non-executable as a way of
disabling its startup at boot time is very common. Probably a
ENABLED=true/false variable in /etc/default/<service> is more common.

So, I think we should remove all those [ -x /usr/sbin/<foo> ] checks in
our init scripts.

Cc'ing Peter, Arnout and Yann to gather additional opinions on this.

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com