For the
benefit of Linux newcomers like me, could someone explain the
historical reasons why we even have a /usr/local directory to begin
with?
Because in many environments /usr is NFS-shared across a lot of
machines.
it goes back before NFS.
the original *nix backup utilities (dump/restore) worked at the
filesystem level. it was much easier as a sysadmin to have backups of
/, /usr and /usr/local so that if you did a system upgrade or
reinstall, you simply installed the OS on / and /usr, then did a full
restore of /usr/local, and you'd instantly get all the site-installed
stuff back. if you didn't do this, system upgrades/reinstalls could
get nightmarish very quickly (and they weren't easy to begin with).
NFS just reinforced the usefulness of this approach. later, solaris
introduced the idea of /opt for the local stuff, but it never really
took off in any other *nix systems AFAIK.
you might be wondering why we have / and /usr ... this so that the
system can boot with just a single filesystem, then come up to
a multiuser state by mounting /usr. putting them in different
filesystems lets you allocate space and administrative controls more
easily. /usr tends to be fairly static in size, and / tends to have
log files and other stuff that grow and are resized fairly often.
--p (once known as <pauld%scr.slb.com(a)bitnet.net>)
