oldlinux-files/Linux-0.95/docs/linux-standards/File_System_Standard

The following is being submitted by Alan Clegg [abc@concert.net] on behalf of
the linux-standards group as the recommended standard for directory file
structure under Linux.

Complete implementation of this file structure is completely voluntary,
and will not be enforced, but will be recommended.  This specification
is released as guidelines for people porting and writing software for
the Linux Operating System to allow easy software installation, upgrade, and
tailoring on already installed systems.

Root Directory:

	Files:
		{none defined by spec}

	Directories:
		bin dev etc home lib mnt usr
	
	Rationale:
		The root directory should not be cluttered with files or
		directories, and should contain no user programs.

/bin Directory:

	Files:
		sh init mount umount dd cat ls fsck mkfs {and as needed}

	Directories:
		{none defined by spec}

	Rationale:
		The /bin directory should contain programs that are vital
		to the restoration of other file systems in the case of 
		a corrupting crash.  No executable in /bin should require
		any other file system to be mounted to execute correctly.

/dev Directory:

	Files:
		{device files}

	Directories:
		{none define by spec}

	Rationale:
		Standard UNIX device files.  This directory should contain
		device entries for all devices that are supported in the
		standard kernel, even if the hardware device does not exist
		on the system.  Note that the distribution will have all
		device files, but they may be removed by the user upon
		system installation.


/etc Directory:

	Files:
		mtab passwd rc ttytab {and as needed}

	Directories:
		{none defined by spec}

	Rationale:
		Standard location of files required during system boot.  Files
		in this directory are usually system specific.  Most will
		require human intervention during system upgrade.

/home Directory:
	
	Files:
		NONE

	Directories:
		{one per user excepting root}

	Rationale:
		Standard location of users home directories.  Will most likely
		be a mounted file system once the system is up.  root's home
		directory should be /.

/lib Directory:

	Files:
		{libraries required for system initialization}

	Directories:
		{none defined by spec}

	Rationale:
		To keep the size of the root partition small (if separate from
		/usr), the files in this directory should only be ones required
		by files in the root partition.

/mnt Directory:
	
	Files:
		NONE

	Directories:
		NONE

	Rationale:
		Standard mount point for external (transient) file systems.
		Must be available for sub-system installation.  Should remain
		as an empty directory.

/tmp Directory:
	
	Files:
		NONE
	
	Directories:
		NONE

	Rationale:
		Temporary file space available for general program use.  May
		become a mounted partition upon system boot.

/usr Directory:

	Files:
		{none defined by spec}

	Directories:
		adm bin spool local lib etc man include src tmp

	Rationale:
		/usr is the mount point for the second major (after root)
		hierarchy of file structure and is discussed in the next
		section.

/usr/adm Directory:

	Files:
		{none defined in spec}

	Directories:
		{none defined in spec}

	Rationale:
		Location of log files and accounting information.

/usr/bin Directory:

	Files:
		{all executable files from standard distribution not contined
		 in /bin}

	Directories:
		{none defined in spec}

	Rationale:
		contains 'drop-in' executables that are considered to be
		standard to the UNIX system. These files should NOT be
		Linux specific, but should have the same function as their
		UNIX equivalents.

/usr/etc Directory:
	
	Files:
		{none defined in spec}

	Directories:
		{none defined in spec}

	Rationale:
		contains configuration files for any files in /usr/bin. helps
		to keep /etc clean and small.

/usr/spool Directory:

	Files:
		{none defined in spec}

	Directories:
		uucp mail

	Rationale:
		containes spool files for mail, printing, uucp transfer, etc.
		May be a mount point for another volume.

/usr/local Directory:

	Files:
		NONE
	
	Directories:
		bin lib etc man src

	Rationale:
		contains files local to the specific system.  will not be
		modified by upgrade process. 

/usr/lib Directory:

	Files:
		libc.a crt0.s {and as needed}

	Directories:
		{none defined in spec}

	Rationale:
		location for library files required for multi-user system
		operation.  This is the directory where program libraries
		should reside.

/usr/man Directory:

	Files:
		NONE
	
	Directories:
		man1 man2 man3 man4 man5 man6 man7 man8
		cat1 cat2 cat3 cat4 cat5 cat6 cat7 cat8

	Rationale:
		Contains manual pages for programs that are standard with
		Linux.

/usr/include Directory:

	Files:
		{programmers include files}

	Directories:
		{as needed}

	Rationale:
		Standard place for system include files.

/usr/src Directory:
	
	Files:
		NONE
	
	Directories:
		bin lib linux usr.bin usr.lib

	Rationale:
		Contains source code for all applications in the release.
		/usr/src/linux contains directories required for kernel builds.

/usr/tmp Directory:

	Files:
		NONE


	Directories:
		NONE

	Rationale:
		Used as additional scratch space for programs.  If /tmp is
		a mounted file system, /usr/tmp may be a symbolic link to
		/tmp.