Rational Unix Filesystem Layout
author Neil Franklin, last modification 2004.10.07

Been thinking a lot about the cruftyness of Unix file system layout
At SUCON'04 listened to speach about "we need better than just patching up"
So decided to put thoughts down in writing, collect them


Bases

/, /usr, /usr/local, /usr/opt, /root, /home/<user>/
  no /var -> /usr/var (no 2 mount point if same partition as /usr)
    some /usr/* symlinks to /usr/var/*, access always via them, never direct
    same for /usr/share, also only access via symlinks into it
  same some /usr/local/* may go to /usr/var/local/*
  same some /usr/opt/<pkg>/* may go to /usr/var/opt/<pkg>/*

PATH (or BASEPATH) shows list of these
BINPATH (PATH) MANPATH etc are seldom needed overrides
  allow $PATH/bin;blah/bin syntax
all paths are evaluated by kernel, as part of name2i processing


Actual Directories

in each base cmd (bin), so (lib/lib*.so), exec (libexec), res (lib/<daten>)
  man/<class>, doc, conf (etc)
  no /sbin, as in /root/bin
  no /usr/sbin, as in /root/bin or /home/<daemonuser>/bin
in / also dev, exec/boot (boot)
in bases other than / also lib (only lib/lib*.a), include, src (code and man)
in /root and /home/<user> their own tmp, no /tmp, no 777 or 1777 dirs at all


Man Pages

man pages for /bin also in /man, not /usr/man
  as no /bin/groff they must be prerendered like in BSD
    groff->ascii is regarded as compiling man page, like c->bin for code
man/<class> is class=bin|exec|conf|lib|... like dir names


Configuration and Preferences

conf files also in /usr[|/local|/opt/<pkg>], for programs in same bases
  /conf only the few configs for /bin stuff
users /home/<user>/.conf stuff in /home/<user>/conf


Users

/etc/passwd -> /conf/users, also possibly a directory not file, entry per user
  only username:UID:GIDs:home, shell from /home/<user>/conf/shell
/etc/shadow -> /home/<user>/conf/password
/etc/group merged into /conf/users, same numeric range, no duplicate defs

ev /root -> /admin, and same for user name


Daemons

for daemons /home/<daemonuser> with bin man conf tmp run spool log