[TUHS] /bin vs /sbin

[Warner Losh]

On Tue, Jul 21, 2020 at 12:23 PM <arnold at skeeve.com> wrote:

> Grant Taylor via TUHS <tuhs at minnie.tuhs.org> wrote:
>
> > To me, this makes it fairly self evident that /sbin was originally for
> > statically linked binaries.  At least in Linux.
>
> Dunno about that.
>

I'm skeptical as well.


> > Does anyone have any history of /sbin from other traditional Unixes?
> > I'd be quite interested in learning more.
>
> /sbin and /usr/sbin came into being in the late 80s when Berkeley
> and USG were standardizing on file system layouts for diskless
> workstations;
> Sun and DEC and others were also in on this.
>
> /sbin specifically was meant to hold the executables meant for use by
> root that previously had been in /etc along with config files.
> (sbin ==> super-user bin.)
>

/sbin showed up in 4.3-Reno (1990), but wasn't in 4.3-Tahoe (1988). This
predates Linux by a year or so.  The changes were due to the filesystem
standardization and layout changes prompted by, among other things,
diskless workstations as you stated later.  Sun's NFS drove a lot of the
adaptation in this area since it quickly became the de-facto network file
system (though others did exist).


> The idea was that /etc held things specific to a box, while /bin, /sbin,
> /usr could be remote mounted from a server.  This is also when /home
> came into practice as the place to hold home directories.
>
> This avoided having umpteen zillion copies of the same files
> (executables, man pages, libraries, etc.) since they could be mounted
> read-only from one or a few servers.  At the time, disk space was not
> nearly as cheap as it is now.
>

A big cost savings in having 20 diskless workstations was that you didn't
need the 2-4gb of disks for each individual one, but instead could have one
copy of the 100MB-200MB of the core OS. When. X started getting libraries
out the wazoo with toolkit wars, it saved even more. IIRC, the Sun 3/50's
ethernet port was faster than its disk port, so your diskless workstation
could be faster than one with a disk (assuming the network wasn't
overloaded).

>From an era that will be remembered best by "The network is the connector"
corruption of a famous marketing slogan...


> This is also when /var came into being for log files and such;
> again - it was per machine space, so it lived either on a small disk
> in the workstation or on a per-client chunk of space on the server
> if the client was totally diskless.
>

All true.

Warner
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