FILESYSTEM(7) Miscellaneous Information Manual FILESYSTEM(7) NAME filesystem - file system organization SYNOPSIS / /usr DESCRIPTION The SunOS file system tree is organized for easy administration. 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 directo- ries. This organization allows the sharable files to be stored on one ma- chine, while being accessed by many machines using a remote file access mechanism such as Sun's Network File System (NFS). Grouping together simi- lar 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(8) program attaches mountable file sys- tems to the file system tree at mount points (directory entries) in the root file system, or other previously mounted file systems. Two file sys- tems, / (the root) and /usr, must be mounted in order to have a fully func- tional system. The root file system is mounted automatically by the kernel at boot time; the /usr file system is mounted by the /etc/rc.boot script, which is run as part of the booting process. 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 MAKEDEV command (see makedev(8)) builds device files in the /dev directory. 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. /home Mount points for home directories. This directory may be arranged so that shared user files are placed under the directory /home/machine-name on machines serving as file servers. Machines may then be locally configured with mount points under /home for all of the file servers of interest, with the name of the mount point being the name of the file server. /mnt A generic mount point. This is an empty directory available for temporarily mounting file systems on. /sbin Executable programs that are needed in the boot process before /usr is mounted. /sbin contains only those programs that are needed in order to mount the /usr file system: hostname(1), if- config(8C), init(8), mount(8), and sh(1). After /usr is mounted, the full complement of utilities are available. /tmp Temporary files that are deleted at reboot time. /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(8), at(1), etc. /var/tmp Transitory files that are not deleted at reboot time. 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 archi- tecture-independent shareable files. The subtree rooted at /usr/share con- tains 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 ma- chines 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 sys- tem contains the following subdirectories: /usr/5bin System V executables. /usr/5include System V include files. /usr/5lib System V library files. /usr/bin Executable programs. The bulk of the system util- ities are located here. /usr/dict Dictionary databases. /usr/etc Executable system administration programs. /usr/games Executable game programs and data. /usr/include Include files. /usr/lib Program libraries and various architecture-depen- dent databases. /usr/pub Various data files. /usr/ucb Executable programs descended from the Berkeley Software Distribution. /usr/share Subtree for architecture-independent shareable files. /usr/share/man Subdirectories for the on-line reference manual pages. /usr/share/lib Architecture-independent databases. A machine with disks may export root file systems, swap files and /usr file systems to diskless or partially-disked machines, which mount these into the standard file system hierarchy. The standard directory tree for ex- porting these file systems is: /export The root of the exported file system tree. /export/exec/architecture-name The exported /usr file system supporting architec- ture-name for the current release. /export/exec/architecture-name.release-name The exported /usr file system supporting architec- ture-name for SunOS release-name. /export/share The exported common /usr/share directory tree. /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. /export/dump/hostname The exported dump file for hostname. /export/crash/hostname The exported crash dump directory for hostname. Changes from Previous Releases The file system layout described here is quite a bit different from the layout employed previous to release 4.0 of SunOS. For compatibility with earlier releases of SunOS, and other versions of the UNIX system, 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. /etc/termcap --> /usr/share/lib/termcap /usr/5lib/terminfo --> /usr/share/lib/terminfo /usr/lib/me --> /usr/share/lib/me /usr/lib/ms --> /usr/share/lib/ms /usr/lib/tmac --> /usr/share/lib/tmac /usr/man --> /usr/share/man The following program binaries have been moved from /etc to /usr/etc with symbolic links to them left in /etc: arp, clri, cron, chown, chroot, con- fig, dkinfo, dmesg, dump, fastboot, fasthalt, fsck, halt, ifconfig, link, mkfs, mknod, mount, ncheck, newfs, pstat, rdump, reboot, renice, restore, rmt, rrestore, shutdown, umount, update, unlink, and vipw. In addition, some files and directories have been moved with no symbolic link left behind in the old location: Old Name New Name /etc/biod /usr/etc/biod /etc/fsirand /usr/etc/fsirand /etc/getty /usr/etc/getty /etc/in.rlogind /usr/etc/in.rlogind /etc/in.routed /usr/etc/in.routed /etc/in.rshd /usr/etc/in.rshd /etc/inetd /usr/etc/inetd /etc/init /usr/etc/init /etc/nfsd /usr/etc/nfsd /etc/portmap /usr/etc/portmap /etc/rpc.lockd /usr/etc/rpc.lockd /etc/rpc.statd /usr/etc/rpc.statd /etc/ypbind /usr/etc/ypbind /usr/lib/sendmail.cf /etc/sendmail.cf /usr/preserve /var/preserve /usr/lib/aliases /etc/aliases /stand /usr/stand /etc/yp /var/yp Note: with this new file system organization, the approach to repairing a broken file system changes. One must mount /usr before doing an fsck(8), for example. If the mount point for /usr has been destroyed, /usr can be mounted temporarily on /mnt or /tmp. If the root file system on a stand- alone system is so badly damaged that none of these mount points exist, or if /sbin/mount has been corrupted, the only way to repair it may be to re- install the root file system. SEE ALSO at(1), ex(1), hostname(1), sh(1), vi(1), intro(4), nfs(4P), hier(7), fsck(8), ifconfig(8C), init(8), makedev(8), mount(8), rc(8) 10 January 1988 FILESYSTEM(7)
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO
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