sysvinit-core: shutdown should default to -h

[Jonathan de Boyne Pollard]

Jesse Smith:

> 881490 (Feature requests asks that, when user provides no valid action 
> for shutdown that we immediately power off, killing any running 
> processes. This sounds terrible/dangerous and we will not implement it 
> upstream. Report can be closed.)
>

This is a wildly inaccurate description of M. Thibault's request; unless 
this counts as an admission that the -h flag to the van Smoorenburg 
/sbin/shutdown is terrible and dangerous, and causes an immediate power 
off. (-:

This is simply a request, as already mentioned in the bug report, that 
-h be a no-op, and that what -h did now be the default behaviour.  It is 
motivated by compatibility with the shutdown commands from some other 
toolsets (It is not only systemd's shutdown that makes what -h did the 
default behaviour.) and by the premise that users will expect shutdown 
to have a particular new syntax.

That said:

van Smoorenburg init is one of the two system management systems that 
actually has a native concept of run levels in the first place (the 
other one not being available in Debian).  Shutting down to "run level 
1" in the absence of -h or -r options still has meaning for it, even if 
it has not for everyone else.

There's quite a lot different between the several shutdown programs of 
different toolsets anyway.  There is not a de facto standard; even 
considering just Debian alone, let alone looking to upstart, real Unix 
toolsets, the BSDs, and suchlike.  Debian's shutdown shim added to runit 
does not support any option other than -f, for example.  And that is 
undocumented.

* https://manpages.debian.org/unstable/runit-init/shutdown.8.en.html

* http://uw714doc.sco.com/en/man/html.1M/shutdown.1M.html

* http://manpages.ubuntu.com/manpages/trusty/man8/shutdown.8.html

* http://netbsd.gw.com/cgi-bin/man-cgi?shutdown+8

* https://man.openbsd.org/shutdown

* 
https://www.ibm.com/support/knowledgecenter/ssw_aix_71/com.ibm.aix.cmds5/shutdown.htm

* http://jdebp.eu./Softwares/nosh/guide/shutdown.html