28 Sep
2018
28 Sep
'18
6:23 p.m.
On Fri, 28 Sep 2018, Tony Finch wrote:
And the 4.3BSD docs show the /a, /b, /c
https://www.tuhs.org/cgi-bin/utree.pl?file=4.3BSD/usr/man/man8/adduser.8
Traditionally, user files live on a file system different from /usr.
Typically the user file systems are mounted on a directories in the
root named sequentially starting from from the beginning of the
alphabet, eg /a, /b, /c, etc. On each such file system there are
subdirectories there for each group of users, i.e.: ``/a/staff'' and
``/b/prof''. This is not strictly necessary but keeps the number of
files in the top level directories reasonably small.
By the way, Berkeley early on (at time of the first Berkeley tape) had a
separate /etc/htmp database to list user's home (or alternate home)
directories (so didn't have to search "large password files" which were
"unreasonably slow") and terminal type (part of the precursor to
termcap). The home's then were like /mnt/staff/mosher,
/mnt/quals/katseff, /mnt/chuck/, /mnt/jeff. Joy's early 2BSD csh docs
show /mnt/bill and /usr/ken as "home directory" examples. And 3BSD's
adduser docs show:
Traditionally, user files live on the file system /mnt and there are
subdirectories there for each group of users, i.e.:
``/mnt/staff'' and ``/mnt/prof''.
This got changed for 4BSD (4.0BSD):
Traditionally, user files live on a file system which has the machines
single letter net(1) address as the first of two characters. Thus on
the Berkeley CS Department VAX, whose Berknet address is ``csvax''
abbreviated ``v'' the user file systems are mounted on ``/va'',
``/vb'', etc. On each such filesystem there are subdirectories
there for each group of users, i.e.: ``/va/staff'' and ``/vb/prof''.
This is not strictly necessary but keeps the number of files in the
top level directories reasonably small.
(where net(1) is Schmidt's Berkeley Network)
As for 4.3BSD the only reference I find of /home is from the aardvark
game from Mike Urban of UCLA (/home/urban). (That is the earliest
reference of a directory called /home/ I found.)
I
intentionally eschew /home on a few systems. 4.4BSD had a convention of
placing user home directories in /a, /b, etc. 4.4BSD-Lite also had
/var/users. Both of which I occasionally use.
The /a convention seems to go back quite a long way. I was looking through
old password files to see where the home directories were, e.g.
https://www.tuhs.org/cgi-bin/utree.pl?file=4.1cBSD/etc/passwd
has a lot of /a/guest whereas 4.3BSD has /usr/guest