Re: why are there /bin and /usr/bin...
On Tue, Aug 10, 2010 at 03:15:35AM -0600, Bruce Sass wrote:
> /sbin and /usr/sbin, /lib and /usr/lib directories?
>
> AFAICT, the reason is so that a minimal but functional system is
> guaranteed to exist so long as a local HDD with a root filesystem is
> available (which doesn't necessarily include /usr); and that is a good
> thing to have because it gives developers a core set of software tools
> they can count on to always exist and facilitates troubleshooting or
> repairs if something breaks (e.g., bug# 592361, where I've worked
> around the problem by using /bin/nano to reconfigure the box with a
> static IP address).
Not just to repair. First of all, / must have enough tools to
bring the system up to the point where the other file systems can be
mounted (i.g., over the network).
> If that is a good reason, perhaps even The reason, for having both /bin
> and /usr/bin, etc., then doesn't it follow that all files required by
> executables residing in /bin and /sbin should also be available so long
> as a local HDD with a root filesystem is available (otherwise those
> executables are either broken or crippled)?
All files that a tool requires to operate must be there, for sure.
> I suppose there could be cases where the broken or crippled
> functionality is not useful or required when a properly populated /usr
> doesn't exist, but I expect those would be "special" cases, because,
> generally, crippled or broken programs are a bad thing. ya?
Can you give examples of such special cases?
> I'm trying to understand the logic behind it not being an automatic bug
> (i.e., something which is a good candidate to check for at build-time)
> for stuff in /bin and /sbin to require stuff in /usr; and I've gotten
> onto this because of bugs like #592361 and #589123, and the observation
> that over the last couple/few years I seem to be running up against
> problems related to this issue more and more frequently.
This is an unfortunate consequence of the fact that less and less
developers separate /, /usr, /var, etc. partitions on their machines.
In the past I always did it on my workstations, however, stopped doing
it around the time of lenny's release.
> With bugs in scripts (e.g., #589123) it should be good enough that a
> text editor is available, but with broken binaries (e.g., #592361) the
> potential to be put in a not-so-easy-to-fix situation is pretty high
> (remember, dpkg is not around when /usr is missing and the fix is going
> to arrive in a .deb)--so maybe that one should generate a warning of
> some sort.
Well, just the other day I was helping a user on #debian to repare his
Debian installation, using mostly sed to edit the config files. Nano
was not functional without /usr and it seemed he did not have any
other editor.
--
Stanislav
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