michael hast wrote:
> Is it me, or does a distrobution install and do apps configure
> slightly differently on each machine? Is that why it is so hard to
> get step-by-step how-to's on so much Linux stuff? It seems like as
> hard as I try, I simply cannot come up with the same exact results
> from machine to machine without playing with stuff. Am I on to
> something here?
Yes.
Every Linux distribution has one thing in common: they use a Linux kernel.
Every distribution uses a _different_ kernel source tree, each
maintaining its own patchset against some vanilla base version of the
Linux kernel.
Every Linux kernel build is different. That's why kernels are "versioned".
Along with the changes in the kernel source, every kernel has a
different kernel configuration, tuned for a target hardware platform and
architecture.
This means that the "drivers" for any given hardware are highly
dependant on your distribution's kernel source and configuration.
(This is the cause of most frustration with getting devices like sound
drivers to work.)
Most Linux distributions today tend to have the same userspace layout,
ala FHS (http://www.pathname.com/fhs/), all divergent.
Each Linux distribution has its own packaging system, be it RPM, DEB,
ebuild, tarball (tgz), etc.
Every distribution package is built based against some "vanilla"
sourcebase of the original OpenSource tool author.
Every distribution package has a configuration mechanism usually bolted
on top of the OpenSource tool (debconf, /etc/defaults, etc).
Every distribution package has a revision history of "package behaviors"
for upgrading and otherwise configuring a package.
Every OpenSource tool has a revision history that often causes
incompatibilities between versions (that must be accounted for by the
distribution).
Every OpenSource tool usually has a community of supporters with custom
source patches for "extra" (often not-fully tested) features.
And then you have issues like the conflicting tools that fight for each
other for the same basic underlying function.
From the ground up, you have layers of encapsulation and cruft to deal
with.
So, you are correct. Depending on the version and patches to the
underlying OpenSource tool, and depending on the version and behavior of
the distribution's packaging of that OpenSource tool (and any other
patches and configuration changes added by that packaging), you will
find that many of the same software tools will behave slightly
differently between distributions.
I'm know I'm overlooking some of the detail above (autoconf configure
--prefix flags, --sysconfdir config trees, etc), but you get the idea.
This is the nightmare of software. This is why we maintain our _own_
distribution of Linux, based loosely on Debian.
It's the only way to ensure the same behavior across a _large_ Linux
server cluster.
-- - Ian C. Blenke <icblenke@nks.net>
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