filesystem(7) DG/UX 5.4R3.00 filesystem(7)
NAME
filesystem - file system organization
SYNOPSIS
/
/usr
DESCRIPTION
The DG/UX directory tree is organized to make system administration
via the sysadm(1M) program easier. Distinct areas within the
directory system tree are provided for files that are private to one
machine, files that can be shared by multiple machines of a common
architecture, files that can be shared by all machines, and home
directories. This organization allows the sharable files to be
stored on one machine, while being accessed by many machines using a
remote file access mechanism such as NFS. Grouping together similar
files makes the file system tree easier to upgrade and manage.
The file system tree consists of a root file system and a collection
of mountable file systems. The mount(1M) program attaches mountable
file systems to the file system tree at mount points (directory
entries) in the root file system, or other previously mounted file
systems. Two file systems, / (the root) and /usr, must be mounted in
order to have a fully functional system. The / (root) and usr file
systems are mounted automatically by the kernel at boot time.
The root file system contains files that are unique to each machine;
it can not be shared among machines. The root file system contains
the following directories:
/dev Character and block special files. Device files
provide hooks into hardware devices or operating
system facilities. The kernel builds new device
files in the /dev directory at every boot.
Typically, device files are built to match the
kernel and hardware configuration of the machine.
/etc Various configuration files and system
administration databases that are machine specific.
You can think of /etc as the ``home directory'' of
a machine, defining its ``identity.'' Executable
programs are no longer kept in /etc.
/sbin The minimum executable programs that are needed to
get a system running. /sbin contains only those
programs that are needed in order to mount the /usr
file system: autocon(1M), fsck(1M), init(1M),
mount(1M), sh(1M), and su(1M), After /usr is
mounted, the full complement of utilities are
available.
/srv A directory tree used by the sysadm(1M) program to
manage various operating system releases and
clients.
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filesystem(7) DG/UX 5.4R3.00 filesystem(7)
/tmp Temporary files that may be deleted.
/var Files, such as log files, that are unique to a
machine but that can grow to an arbitrary
(``variable'') size.
/var/adm System logging and accounting files.
/var/preserve Backup files for vi(1) and ex(1).
/var/spool Subdirectories for files used in printer spooling,
mail delivery, cron(1), at(1), etc.
/var/tmp Temporary files that may be deleted.
/tmp and /var/tmp should contain files which may be deleted.
Administrators who want to clean out /tmp and /var/tmp periodically
should do so via cron jobs similar to the ones in
/var/spool/cron/crontabs.
Because it is desirable to keep the root file system small, larger
file systems are often mounted on /var and /tmp.
The file system mounted on /usr contains architecture-dependent and
architecture-independent shareable files. The subtree rooted at
/usr/share contains architecture-independent shareable files; the
rest of the /usr tree contains architecture-dependent files. By
mounting a common remote file system, a group of machines with a
common architecture may share a single /usr file system. A single
/usr/share file system can be shared by machines of any architecture.
A machine acting as a file server may export many different /usr file
systems to support several different architectures and operating
system releases. Clients usually mount /usr read-only to prevent
their accidentally modifying any shared files. The /usr file system
contains the following subdirectories:
/usr/bin
Executable user commands.
/usr/catman
Contains the online manual reference pages.
/usr/dglib
DG/UX-specific program libraries and architecture-dependent
databases.
/usr/etc
Executable system administration programs.
/usr/include
Include files.
/usr/lib
Program libraries and various architecture-dependent
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filesystem(7) DG/UX 5.4R3.00 filesystem(7)
databases.
/usr/opt
Contains application packages.
/usr/pub
Various data files.
/usr/release
Contains media notices, release notices, and system package
names.
/usr/sbin
Commands used by a system administrator.
/usr/sbin/init.d
Contains the executable files for setting system run levels.
/usr/src
Parent directory for source code.
/usr/stand
Contains stand-alone utilities and bootstrap programs.
/usr/ucb
Executable programs descended from the Berkeley Software
Distribution.
/usr/share
Subtree for architecture-independent shareable files.
A machine with disks may export root file systems, swap files and
/usr file systems to operating system clients (with or without
disks), which mount these into the standard file system hierarchy.
The standard directory tree for exporting these file systems is:
/srv The root of the exported directory tree.
/srv/admin Contains the sysadm databases and
information files.
/srv/release Contains space for each release's usr and
client roots.
/srv/share Contains release-independent shared
software.
/srv/swap Swap space on a one-per-client basis.
/srv/release/PRIMARY Contains symbolic links to the server's /usr
and / files.
/srv/release/PRIMARY/root/hostname
The root file system for OS client hostname.
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filesystem(7) DG/UX 5.4R3.00 filesystem(7)
/srv/release/PRIMARY/root/Kernels
Contains the shared kernels for one or more
OS clients. An OS client's kernel and root
directory must reside in the same file
system for a successful network boot.
Changes from Previous Releases
For compatibility with historical releases, symbolic links are
provided for various files and directories linking their previous
names to their current locations. The symbolic links provided
include:
/bin --> /usr/bin All programs previously located
in /bin are now in /usr/bin.
/lib --> /usr/lib All files previously located in
/lib are now in /usr/lib.
/usr/adm --> /var/adm The entire /usr/adm directory
has been moved to /var/adm.
/usr/spool --> /var/spool The entire /usr/spool directory
has been moved to /var/spool.
/usr/tmp --> /var/tmp The /usr/tmp directory has been
moved to /var/tmp.
SEE ALSO
hostname(1), sh(1), fsck(1M), ifconfig(1M), init(1M), mount(1M),
sysadm(1M), intro(4).
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