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

[Richard Kreuter]

On Mon, May 20, 2002 at 07:48:38PM -0700, Thomas Bushnell, BSG wrote:
> Richard Kreuter <kreuter@ausar.rutgers.edu> writes:
> 
> >   At this point, though, the draft doesn't point out any distinctions
> > between GNU and GNU/Linux systems, so the whole thing can be dropped.
> > Whichever expression everybody (give or take) likes best is the right
> > way to go.
> 
> I think we should just say GNU/Hurd, for political reasons if none
> other.  I think it will make it easier to get the document adopted.

  Okay.

  Here's the current draft, with all references to the operating
system as GNU/Hurd, and with a few example servers under /hurd.  Same
punctuation: +++ changed since last time, <> 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 /lib/modules is not the right place for kernel modules. 
It should be moved it to the GNU/Linux specific annex.

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

6.2  GNU/Hurd

This is the annex for the GNU/Hurd operating system.  The GNU/Hurd
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/Hurd, GNU/Linux, or other systems may maintain
symbolic links to files whose locations on GNU/Hurd 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 files, or symbolic links to files, used for system boot
and recovery, must be located in /bin:

settrans        Command to set/remove translators
showtrans       Translator setting information utility
fsysopts        File system option manipulator


The following utilities may be omitted from /bin:

dmesg      Utility to print or control the kernel message buffer
mount      Utility to mount a filesystem
umount     Utility to unmount file systems

The GNU/Hurd 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. The following
files, or symbolic links to files, must be in /bin if the
corresponding subsystem is installed:

fdisk      Partition table manipulator (optional)
fsck       File system check and repair utility (optional)
fsck.*     File system check and repair utility for a specific filesystem 
(optional)
mkfs       Command to build a filesystem (optional)
mkfs.*     Command to build a specific filesystem (optional)
parted     Partition table and file system manipulator (optional)


6.2.x  /com : Shareable, variable data.

The /com hierarchy contains files architecture-independent 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.

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 files may be found under /hurd:
system:

+++ext2fs       second extended file system translator server
+++ftpfs        ftp filesystem translator server
+++hello        familiar, friendly greeting (and more) translator server
+++hostmux      host relay translator server <?>
+++isofs        iso9660 file system translator server
+++nfs          network file system translator server
+++symlink      symbolic link translator server
+++usermux      <mumble, mumble...?>
+++ufs          ufs file system translator server
<What else?  What should be removed?>

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    Telnet protocol daemon
in.ftpd         Ftp protocol daemon
sendmail      Internet mail transport agent

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 files, or symbolic links to files, may be found in /bin:

devprobe   Hardware device detection utility

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.

In addition, all files with names of the form /servers/socket/N, where
N is a string of digits, are reserved as rendezvous points for domain
socket translators. 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/local  A symbolic link to /servers/socket/1
/servers/socket/inet   A symbolic link to /servers/socket/2.

6.2.x  /usr : Secondary Hierarchy

In the GNU/Hurd system, /usr is a symbolic link to . in the root directory.
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 will have a special filesystem, called shadowfs, which
will be able to "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 may exist as the primary GNU/Hurd Info system directory.

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