filesystem(7) filesystem(7)
NAME
filesystem - file system organization
SYNOPSIS
/
/usr
DESCRIPTION
The System V file system tree is organized for administrative
convenience. Distinct areas within the file 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 sharable files to be
stored on one machine but 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. If /usr is configured
as a separate file system, it must be mounted in order to have
a completely functional system. The root file system is
mounted automatically by the kernel at boot time.
The root file system contains files that are unique to each
machine. It contains the following directories:
/dev Character and block special files. These device
files provide hooks into hardware devices or
operating system facilities. Typically, device
files are built to match the kernel and hardware
configuration of the machine.
/dev/term Terminal devices.
/dev/pts Pseudo-terminal devices.
/dev/sxt Shell layers device files used by shl.
/etc Machine-specific administrative configuration files
and system administration databases. /etc may be
viewed as the home directory of a machine, the
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directory that in a sense defines the machine's
identity. Executable programs are no longer kept
in /etc.
/home Root of a subtree for user directories.
/mnt Temporary mount point for file systems. This is an
empty directory on which file systems may be
temporarily mounted.
/opt Root of a subtree for add-on application packages.
/proc Root of a subtree for the process file system.
/sbin Essential executables used in the booting process
and in manual system recovery. The full complement
of utilities is available only after /usr is
mounted,
/tmp Temporary files; initialized to empty during the
boot operation.
/var Root of a subtree for varying files. Varying files
are files that are unique to a machine but that can
grow to an arbitrary (that is, variable) size. An
example is a log file.
/var/adm System logging and accounting files.
/var/cron cron's log file.
/var/mail Where users' mail is kept.
/var/opt Top-level directory used by application packages.
/var/preserve
Backup files for vi(1) and ex(1).
/var/spool Subdirectories for files used in printer spooling,
mail delivery, cron(1M), at(1), etc.
/var/tmp Transitory files; initialized to empty during the
boot operation.
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filesystem(7) filesystem(7)
Because it is desirable to keep the root file system small and
not volatile, on disk-based systems larger file systems are
often mounted on /home, /opt, /usr, and /var.
The file system mounted on /usr contains architecture-
dependent and architecture-independent sharable files. The
subtree rooted at /usr/share contains architecture-independent
sharable 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 so that they don't accidentally change any shared files.
The /usr file system contains the following subdirectories:
/usr/bin Most system utilities.
/usr/sbin Executables for system administration.
/usr/games Game binaries and data.
/usr/include
Include header files (for C programs, etc).
/usr/lib Program libraries, various architecture-dependent
databases, and executables not invoked directly by
the user (system daemons, etc).
/usr/share Subtree for architecture-independent sharable files.
/usr/share/man
Subdirectories for on-line reference manual pages
(if present).
/usr/share/lib
Architecture-independent databases.
/usr/src Source code for utilities and libraries.
/usr/ucb Berkeley compatibility package binaries.
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/usr/ucbinclude
Berkeley compatibility package header files.
/usr/ucblib
Berkeley compatibility package libraries.
A machine with disks may export root file systems, swap files,
and /usr file systems to diskless or partially-disked machines
that mount them into the standard file system hierarchy. The
standard directory tree for sharing these file systems from a
server is:
/export The default root of the exported file system tree.
/export/exec/architecture-name
The exported /usr file system supporting
architecture-name for the current release.
/export/exec/architecture-name.release-name
The exported /usr file system supporting
architecture-name for System V release-name.
/export/exec/share
The exported common /usr/share directory tree.
/export/exec/share.release-name
The exported common /usr/share directory tree for
System V release-name.
/export/root/hostname
The exported root file system for hostname.
/export/swap/hostname
The exported swap file for hostname.
/export/var/hostname
The exported /var directory tree for hostname.
REFERENCES
at(1), fsck(1M), init(1M), mknod(1M), mount(1M), sh(1), vi(1)
Copyright 1994 Novell, Inc. Page 4