Date: Fri, 20 Feb 2015 21:27:33 -0800 From: perryh@pluto.rain.com (Perry Hutchison) To: jilles@stack.nl Cc: freebsd-hackers@freebsd.org Subject: Re: RFC: make init(8) aware of /rescue/sh Message-ID: <54e81745.VJ9sLUeKwo661VPr%perryh@pluto.rain.com> In-Reply-To: <20150214234943.GB1360@stack.nl> References: <54db2f2f.gIXyruGSeJuY3FbJ%perryh@pluto.rain.com> <20150214234943.GB1360@stack.nl>
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Jilles Tjoelker <jilles@stack.nl> wrote: > On Wed, Feb 11, 2015 at 02:30:07AM -0800, Perry Hutchison wrote: > > Seems to me it might be desirable for init(8) to fall back > > to /rescue/sh for single-user mode if neither the default > > (kenv:init_shell) nor /bin/sh is usable. Thoughts? [patch snipped] > It is already possible to type "/rescue/sh" at the prompt > (the Makefile always compiles with -DDEBUGSHELL). Of course, provided one remembers that /rescue/sh exists :) I use /rescue so rarely that I did not remember its existence when this situation arose a little over a week ago. (I did, however, remember that I have an emergency shell in /sbin; worst case I would have booted off the distribution flash drive, which I keep handy in case of boot troubles.) Part of the reason for adding an automatic fallback to /rescue/sh is to jog the admin's memory, in case something is messed up badly enough that other parts of /rescue might also be needed. > This must be done manually but also covers the case where > /bin/sh exists but rtld or shared libraries are missing or > broken. That case is already covered, indeed it is exactly what led to the incident mentioned above. (/bin/sh was fine, but one of its shared libs was missing.) > I'm not really sure this is worth the extra code. If we follow that line of reasoning to its logical conclusion, we should also remove the automatic fallback to _PATH_BSHELL. After all, if the system fails to boot because kenv:init_shell is set to something broken, one can always enter /bin/sh manually. BTW the amount of "extra code" is trifling compared to the overall size of init :)
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