svn commit: r293227 - head/etc

[Ian Lepore]

On Tue, 2016-01-05 at 16:35 -0800, Devin Teske wrote:
> > On Jan 5, 2016, at 4:27 PM, Ian Lepore <ian at freebsd.org> wrote:
> > 
> > On Tue, 2016-01-05 at 19:18 -0500, Allan Jude wrote:
> > > On 2016-01-05 19:16, Devin Teske wrote:
> > > > 
> > > > > On Jan 5, 2016, at 4:00 PM, Ian Lepore <ian at freebsd.org>
> > > > > wrote:
> > > > > 
> > > > > On Tue, 2016-01-05 at 21:20 +0000, Warner Losh wrote:
> > > > > > Author: imp
> > > > > > Date: Tue Jan  5 21:20:47 2016
> > > > > > New Revision: 293227
> > > > > > URL: https://svnweb.freebsd.org/changeset/base/293227
> > > > > > 
> > > > > > Log:
> > > > > >  Use the more proper -f. Leave /bin/rm in place since
> > > > > > that's
> > > > > > what
> > > > > >  other rc scripts have, though it isn't strictly necessary.
> > > > > > 
> > > > > > Modified:
> > > > > >  head/etc/rc
> > > > > > 
> > > > > > Modified: head/etc/rc
> > > > > > ===========================================================
> > > > > > ====
> > > > > > ======
> > > > > > =========
> > > > > > --- head/etc/rc	Tue Jan  5 21:20:46 2016	(r29
> > > > > > 3226
> > > > > > )
> > > > > > +++ head/etc/rc	Tue Jan  5 21:20:47 2016	(r29
> > > > > > 3227
> > > > > > )
> > > > > > @@ -132,9 +132,9 @@ done
> > > > > > # Remove the firstboot sentinel, and reboot if it was
> > > > > > requested.
> > > > > > if [ -e ${firstboot_sentinel} ]; then
> > > > > > 	[ ${root_rw_mount} = "yes" ] || mount -uw /
> > > > > > -	/bin/rm ${firstboot_sentinel}
> > > > > > +	/bin/rm -f ${firstboot_sentinel}
> > > > > > 	if [ -e ${firstboot_sentinel}-reboot ]; then
> > > > > > -		/bin/rm ${firstboot_sentinel}-reboot
> > > > > > +		/bin/rm -f ${firstboot_sentinel}-reboot
> > > > > > 		[ ${root_rw_mount} = "yes" ] || mount -ur /
> > > > > > 		kill -INT 1
> > > > > > 	fi
> > > > > > 
> > > > > 
> > > > > Using rm -f to suppress an error message seems like a bad
> > > > > idea
> > > > > here --
> > > > > if the sentinel file can't be removed that implies it's going
> > > > > to
> > > > > do
> > > > > firstboot behavior every time it boots, and that's the sort
> > > > > of
> > > > > error
> > > > > that should be in-your-face.  Especially on the reboot one
> > > > > because
> > > > > you're going to be stuck in a reboot loop with no error
> > > > > message.
> > > > > 
> > > > 
> > > > Leaving off -f so that the user gets prompted isn't quite as
> > > > helpful
> > > > as, say, using -f but then testing to make sure the file is
> > > > really
> > > > gone
> > > > (if it still exists after a silent "rm -f", put up an
> > > > informative
> > > > warning
> > > > instead of asking the user if they would like to delete it).
> > > > 
> > > > The end-result of having something thrown in your face seems
> > > > desirable. Having a prompt that asks you if you'd like to
> > > > delete it
> > > > (even if there is an error immediately above it explaining it
> > > > could
> > > > not be deleted) seems nonsensical.
> > > > 
> > > 
> > > More specifically, firstboot is most likely run in situations
> > > where
> > > no 
> > > one will be at the console, so an interactive prompt stopping the
> > > system 
> > > from coming up is bad.
> > > 
> > 
> > I couldn't possibly disagree more.  If you're not paying attention
> > to
> > what happens the first time you boot a freshly installed system,
> > you
> > deserve whatever happens to you.
> 
> What if you are in New York and the server is alone in Siberia?
> 
> ... Got SSH? (not if your boot stopped, you don't)

Unh huh.  And what are you going to do when the server goes
unresponsive because it silently failed to delete firstboot-reboot and
now it's just in an endless reboot loop?

Silent failure is only a viable option for expected errors you can
recover from without intervention.

-- Ian