Re: Hurd FS hierarchy (was Re: LD_LIBRARY_PATH troubles)

[Richard Kreuter]

On Sun, May 05, 2002 at 06:05:41PM +0200, Jeroen Dekkers wrote:
> On Mon, Mar 25, 2002 at 10:52:45PM -0500, Richard Kreuter wrote:
> > On Mon, Mar 25, 2002 at 06:08:49PM +0100, Jeroen Dekkers wrote:
> > > I think it would be nice to post the GNU things to the mailinglist
> > > before they'll release the next version, which will be soon.
> > I've merged what I've understood...
> What's the status of this? Is everything added which need to be added?
> Can we send it to the FHS people?

Here's the very slightly corrected update to the last posting from a
while back.  There are still a few points on which the wording is
incomplete.

If the below copy is suitable, somebody who thinks himself an
authoritative representative for the project ought to submit this to
the relevant FHS list.  If there are still corrections or additions to
be made, I'll try to merge them as quickly as possible.

Lastly, I apologize for the delay.  

Same punctuation: +++ is stuff I added, <> for editorial remarks.

---

The following things need to change in the FHS itself:

3.5.1 Grub may place its configuration file under /boot.

3.9.3 I'm not sure /lib/modules is the right place for kernel
modules. I think we should move it to the GNU/Linux specific annex.

5.6.1 says "it not supported under Linux", which is too OS-specific.

6.2  GNU

This is the annex for the GNU operating system.  We sometimes refer
to this as the GNU/Hurd system, in cases where it is necessary to
distinguish the GNU system from other systems that use large amounts
of GNU software.

The GNU system is special compared to other UNIX-like operating
systems in the way it treats the filesystem namespace. The filesystem
namespace is very flexible, you can do anything with it what you
want. That's why it is reasonable to specify where you should find
directories and files, but not the way those directories and files
should get there.

As a rule, distributors who wish to maintain compatibility between
their distributions of GNU, GNU/Linux, or other systems may maintain
symbolic links for files whose locations on GNU systems differ from
their locations on other systems.  This accomodates programs with
"hard-coded" filenames. +++For example, files that should be found
under /libexec may be symbolic links, or may be the targets of
symbolic links located under /sbin, /bin, and so forth.


6.2.x  / : The Root Filesystem

It's allowed to create a new subdirectory of the root filesystem by
the distribution creator or user.

6.2.x  /boot : Static files of the bootloader

<If the following isn't already in the FHS, then>
+++The configuration file for the grub bootloader may be found under
/boot.

6.2.x  /bin : Essential user command binaries (for use by all users)

The following utilites used for system boot and recovery must be
located in /bin:

settrans
showtrans
fsysopts


The following utilities may be omitted from /bin:

dmesg
mount
umount  

The GNU system has been designed with a goal of providing users with
more power than they have traditionally been afforded on Unix and
Unix-compatible systems.  As a result, several system binaries are
useful to normal users and should be found in /bin:

mkfs.*
mk*fs
*fsck
fsck.*
parted
*fdisk


6.2.x  /com : Shareable, variable data.

The /com hierarchy contains files architecture-independent, sharable
data files which the programs modify while they run.  Some of these
files have been placed in /var or /usr in the past; in case a
distributor wishes to maintain compatibility with systems that expect
to find these files in /var or /usr, symbolic links may be used.

+++Note that files ought to be found in /com in case a majority of
relevant programs that expect to modify the files can do so while the
file is shared among hosts.

BEGIN RATIONALE:

Having recognized the distinction between shareable and non-shareable
mutable data files, the authors of the GNU Coding Standards intend
that all shareable mutable data files be found under a single
directory, to simplify management of shared file hierarchies among
systems.

END RATIONALE

6.2.x  /hurd : The Hurd servers

/hurd contains the Hurd server binaries. Servers with .static appended
to their name must be statically linked servers, servers without
.static appended may be dynamically linked servers.

The following servers, or symbolic links to servers, are required in
/hurd.

auth[.static]  The standard authentication server.
exec[.static]  The standard execution server.
init[.static]  The standard initialization and state maintaining server.
proc[.static]  The standard process server.

6.2.x  /libexec : Executables only run by other programs

The directory for installing executable programs to be run by other
programs rather than by users.

The following are example programs that could be found in /libexec,
if they exist on a system:

in.telnetd
in.ftpd
sendmail

Note that some programs that are normally run only by other programs
may occasionaly be run by users under certain circumstances, such as
debugging.  Nevertheless, such programs are to be found in /libexec.

BEGIN RATIONALE:

A number of programs are intended to be run only by other programs.
These programs therefore don't belong in directories containing
commands for users.

END RATIONALE

6.2.x  /sbin : 

The following utilities may be placed in /bin:

devprobe 

6.2.x  /servers : Standard location where Hurd servers translate

This is the directory Hurd servers translate rendezvous filesystem
nodes in standard locations, so that other programs can easily find
them and use server-specific interfaces.

/servers/crash     The node where the crash server translates.
/servers/exec      The node where the exec sever translates.
/servers/password  The node where the password server translates.
/servers/proc      The node where the process server translates.
/servers/startup           <What's this do?>

In addition, all files with names of the form /servers/socket/N,
where N is a string of digits, are reserved for <somebody who knows
the score to finish this sentence>.  Symbolic links to these files are
also permitted in the /servers/socket directory, as shown in the
example below.

/servers/socket/1  The node where the pflocal server translates.
/servers/socket/2  The node where the pfinet server translates.
/servers/socket/pflocal  A symbolic link to /servers/socket/1
/servers/socket/pfinet   A symbolic link to /servers/socket/2.

6.2.x  /usr : Secondary Hierarchy

In the GNU system, /usr is a symbolic link to /. The / and /usr
directory have thus the same name and names of files and directories
within them must not conflict.

BEGIN RATIONALE

The GNU Hurd has a special filesystem, called shadowfs, which can
"merge" directories. Thus everything from different sources can be
merged (both static and variable data) and /usr isn't really needed,
instead of /usr, everything will be found under /.

END RATIONALE

6.2.x  /usr/share/info

This directory exist as the primary GNU Info system directory.

6.2.x  /usr/share/man  This directory is optional on a GNU system.

6.2.x  /usr/X11R6 : X Window System, Version 11 Release 6

This directory should not be used. Instead the X Window System should
be placed in /.

6.2.x  /var : Mutable, machine-specific data files

The /var hierarchy should normally not contain files that can be
shared among host systems.  These files should instead be found in
/com.

BEGIN RATIONALE:

Having recognized the distinction between shareable and
non-shareable mutable data files, the authors of the GNU Coding
Standards intend that all unshareable mutable data files be found
under a single directory, to simplify management of shareable file
hierarchies among host systems.

END RATIONALE

6.2.x  /var/spool/cron : cron and at jobs

This directory contains the variable data for the cron and at
programs.