<A

NAME="PURPOSE3" >Purpose</A

>

/bin contains commands that may be used by

both the system administrator and by users, but which are required when no other filesystems are mounted (e.g. in single user mode). It may also contain commands which are used indirectly by scripts.

<A NAME="AEN261" HREF="#FTN.AEN261" >[1]</A

<A

NAME="REQUIREMENTS2" >Requirements</A

>

There must be no subdirectories in /bin.

The following commands, or symbolic links to commands, are required in /bin.

If /bin/sh is not a true Bourne shell, it must be a hard or symbolic link to the real shell command.

The [ and test

commands must be placed together in either /bin

<A

NAME="SPECIFICOPTIONS2" >Specific Options</A

>

The following programs, or symbolic links to programs, must be

in /bin if the corresponding subsystem is

If the gunzip and zcat

programs exist, they must be symbolic or hard links to gzip. /bin/csh may be a symbolic link to /bin/tcsh or

<A

NAME="PURPOSE4" >Purpose</A

>

This directory contains everything required for the boot process

except configuration files not needed at boot time and the map installer. Thus /boot stores data that is used before the kernel begins executing user-mode programs. This may include saved master boot sectors and sector map files.

<A NAME="AEN493" HREF="#FTN.AEN493" >[2]</A

<A

NAME="SPECIFICOPTIONS3" >Specific Options</A

>

The operating system kernel must be located in either

/ or /boot.

<A NAME="AEN507" HREF="#FTN.AEN507" >[3]</A

<A

NAME="PURPOSE5" >Purpose</A

>

The /dev directory is the location of special or device files.

<A

NAME="SPECIFICOPTIONS4" >Specific Options</A

>

If it is possible that devices in /dev will

need to be manually created, /dev must contain a command named MAKEDEV, which can create devices as needed. It may also contain a MAKEDEV.local

If required, MAKEDEV must have provisions

for creating any device that may be found on the system, not just

<A

NAME="PURPOSE6" >Purpose</A

>

The /etc hierarchy contains configuration

files. A "configuration file" is a local file used to control the operation of a program; it must be static and cannot be an executable binary.

<A NAME="AEN534" HREF="#FTN.AEN534" >[4]</A

<A

NAME="REQUIREMENTS3" >Requirements</A

>

No binaries may be located under /etc.

<A NAME="AEN540" HREF="#FTN.AEN540" >[5]</A

The following directories, or symbolic links to directories are required in /etc:

<A

NAME="SPECIFICOPTIONS5" >Specific Options</A

>

The following directories, or symbolic links to directories must

be in /etc, if the corresponding subsystem is

The following files, or symbolic links to files, must be in

/etc if the corresponding subsystem is installed:

<A NAME="AEN581" HREF="#FTN.AEN581" >[6]</A

mtab does not fit the static nature of

/etc: it is excepted for historical reasons.

<A NAME="AEN722" HREF="#FTN.AEN722" >[7]</A

<A

NAME="ETCOPTCONFIGURATIONFILESFOROPT" >/etc/opt : Configuration files for /opt</A

>

<A

NAME="ETCX11CONFIGURATIONFORTHEXWINDOWS" >/etc/X11 : Configuration for the X Window System (optional)</A

>

<A

NAME="ETCSGMLCONFIGURATIONFILESFORSGMLAN" >/etc/sgml : Configuration files for SGML (optional)</A

>

<A

NAME="AEN795" >/etc/xml : Configuration files for XML (optional)</A

>

<A

NAME="PURPOSE10" >Purpose</A

>

/home is a fairly standard concept, but it

is clearly a site-specific filesystem.

<A NAME="AEN808" HREF="#FTN.AEN808" >[9]</A >

The setup will differ from host to host. Therefore, no program should rely on this location.

<A NAME="AEN819" HREF="#FTN.AEN819" >[10]</A

<A

NAME="REQUIREMENTS4A" >Requirements</A

>

User specific configuration files for applications are stored in the

user's home directory in a file that starts with the '.' character (a "dot file"). If an application needs to create more than one dot file then they should be placed in a subdirectory with a name starting with a '.' character, (a "dot directory"). In this case the configuration files should not start with the '.' character. <A NAME="AEN826" HREF="#FTN.AEN826" >[11]</A

<A

NAME="PURPOSE11" >Purpose</A

>

The /lib directory contains those shared

library images needed to boot the system and run the commands in the root filesystem, ie. by binaries in /bin and /sbin.

<A NAME="AEN836" HREF="#FTN.AEN836" >[12]</A

<A

NAME="REQUIREMENTS5" >Requirements</A

>

At least one of each of the following filename patterns are required (they may be files, or symbolic links):

If a C preprocessor is installed, /lib/cpp

must be a reference to it, for historical reasons.

<A NAME="AEN866" HREF="#FTN.AEN866" >[13]</A

<A

NAME="SPECIFICOPTIONS7" >Specific Options</A

>

The following directories, or symbolic links to directories,

must be in /lib, if the corresponding subsystem

<A

NAME="PURPOSE12" >Purpose</A

>

There may be one or more variants of the

/lib directory on systems which support more than one binary format requiring separate libraries.

<A NAME="AEN890" HREF="#FTN.AEN890" >[14]</A

<A

NAME="REQUIREMENTS6" >Requirements</A

>

If one or more of these directories exist, the requirements for

their contents are the same as the normal /lib directory, except that /lib<qual>/cpp is not required.

<A NAME="AEN900" HREF="#FTN.AEN900" >[15]</A

<A

NAME="PURPOSEMEDIAMOUNTPOINT" >Purpose</A

>

This directory contains subdirectories which are used as mount

points for removeable media such as floppy disks, cdroms and zip

<A

NAME="SPECIFICOPTIONSMEDIAMOUNT" >Specific Options</A

>

The following directories, or symbolic links to directories,

must be in /media, if the corresponding subsystem

On systems where more than one device exists for mounting a

certain type of media, mount directories can be created by appending a digit to the name of those available above starting with '0', but the unqualified name must also exist.

<A NAME="AEN947" HREF="#FTN.AEN947" >[16]</A

<A

NAME="PURPOSE13" >Purpose</A

>

This directory is provided so that the system administrator may

temporarily mount a filesystem as needed. The content of this directory is a local issue and should not affect the manner in which

This directory must not be used by installation programs: a

suitable temporary directory not in use by the system must be used

<A

NAME="PURPOSE14" >Purpose</A

>

/opt is reserved for the installation of add-on application software packages.

A package to be installed in /opt must

locate its static files in a separate /opt/<package> or /opt/<provider> directory tree, where <package> is a name that describes the software package and <provider> is the provider's LANANA

<A

NAME="REQUIREMENTS7" >Requirements</A

>

The directories /opt/bin,

/opt/doc, /opt/include, /opt/info, /opt/lib, and /opt/man are reserved for local system administrator use. Packages may provide "front-end" files intended to be placed in (by linking or copying) these reserved directories by the local system administrator, but must function normally in the absence

Programs to be invoked by users must be located in the directory

/opt/<package>/bin or under the /opt/<provider> hierarchy. If the package includes UNIX manual pages, they must be located in /opt/<package>/share/man or under the /opt/<provider> hierarchy, and the same substructure as /usr/share/man must be

Package files that are variable (change in normal operation)

must be installed in /var/opt. See the section

Host-specific configuration files must be installed in

/etc/opt. See the section on

No other package files may exist outside the

/opt, /var/opt, and /etc/opt hierarchies except for those package files that must reside in specific locations within the filesystem tree in order to function properly. For example, device lock files must be placed in /var/lock and devices must be

Distributions may install software in /opt,

but must not modify or delete software installed by the local system administrator without the assent of the local system

<A

NAME="PURPOSE15" >Purpose</A

>

The root account's home directory may be determined by developer

or local preference, but this is the recommended default location.

<A NAME="AEN1037" HREF="#FTN.AEN1037" >[17]</A

<A

NAME="PURPOSE16" >Purpose</A

>

Utilities used for system administration (and other root-only

commands) are stored in /sbin, /usr/sbin, and /usr/local/sbin. /sbin contains binaries essential for booting, restoring, recovering, and/or repairing the system in addition to the binaries in /bin.

<A NAME="AEN1051" HREF="#FTN.AEN1051" >[18]</A > Programs executed after /usr is known to be mounted (when there are no problems) are generally placed into /usr/sbin. Locally-installed system administration programs should be placed into /usr/local/sbin.

<A NAME="AEN1058" HREF="#FTN.AEN1058" >[19]</A

<A

NAME="REQUIREMENTS8" >Requirements</A

>

The following commands, or symbolic links to commands, are required in /sbin.

<A

NAME="SPECIFICOPTIONS8" >Specific Options</A

>

The following files, or symbolic links to files, must be in

/sbin if the corresponding subsystem is

<A

NAME="PURPOSE16A" >Purpose</A

>

/srv contains site-specific data which is

served by this system.

<A

NAME="PURPOSE17" >Purpose</A

>

The /tmp directory must be made available for programs that require temporary files.

Programs must not assume that any files or directories in

/tmp are preserved between invocations of the

<A

NAME="PURPOSE19" >Purpose</A

>

This hierarchy is reserved for the X Window System, version 11 release 6, and related files.

To simplify matters and make XFree86 more compatible with the X

Window System on other systems, the following symbolic links must be

    /usr/bin/X11 -> /usr/X11R6/bin
    /usr/lib/X11 -> /usr/X11R6/lib/X11
    /usr/include/X11 -> /usr/X11R6/include/X11

In general, software must not be installed or managed via the above

symbolic links. They are intended for utilization by users only. The difficulty is related to the release version of the X Window System — in transitional periods, it is impossible to know what release of X11 is

<A

NAME="SPECIFICOPTIONS10" >Specific Options</A

>

Host-specific data in /usr/X11R6/lib/X11 should be interpreted

as a demonstration file. Applications requiring information about the current host must reference a configuration file in /etc/X11, which may be linked to a file in /usr/X11R6/lib.

<A NAME="AEN1299" HREF="#FTN.AEN1299" >[21]</A

<A

NAME="PURPOSE20" >Purpose</A

>

This is the primary directory of executable commands on the system.

<A

NAME="SPECIFICOPTIONS11" >Specific Options</A

>

The following directories, or symbolic links to directories,

must be in /usr/bin, if the corresponding

/usr/bin/X11 must be a symlink to /usr/X11R6/bin if the latter exists.

The following files, or symbolic links to files, must be in

/usr/bin, if the corresponding subsystem is

<A

NAME="PURPOSE21" >Purpose</A

>

This is where all of the system's general-use include files for the C programming language should be placed.

<A

NAME="SPECIFICOPTIONS12" >Specific Options</A

>

The following directories, or symbolic links to directories,

must be in /usr/include, if the corresponding

The symbolic link /usr/include/X11 must

link to /usr/X11R6/include/X11 if the latter

<A

NAME="PURPOSE22" >Purpose</A

>

/usr/lib includes object files, libraries,

and internal binaries that are not intended to be executed directly by users or shell scripts. <A NAME="AEN1389" HREF="#FTN.AEN1389" >[22]</A

Applications may use a single subdirectory under

/usr/lib. If an application uses a subdirectory, all architecture-dependent data exclusively used by the application must be placed within that subdirectory.

<A NAME="AEN1394" HREF="#FTN.AEN1394" >[23]</A

<A

NAME="SPECIFICOPTIONS13" >Specific Options</A

>

For historical reasons, /usr/lib/sendmail

must be a symbolic link to /usr/sbin/sendmail if the latter exists.

<A NAME="AEN1402" HREF="#FTN.AEN1402" >[24]</A

If /lib/X11 exists,

/usr/lib/X11 must be a symbolic link to /lib/X11, or to whatever /lib/X11 is a symbolic link to.

<A NAME="AEN1418" HREF="#FTN.AEN1418" >[25]</A

<A

NAME="PURPOSE23" >Purpose</A

>

/usr/lib<qual> performs the same role as /usr/lib for an

alternate binary format, except that the symbolic links /usr/lib<qual>/sendmail and /usr/lib<qual>/X11 are not required.

<A NAME="AEN1435" HREF="#FTN.AEN1435" >[26]</A

<A

NAME="USRLOCALLOCALHIERARCHY" >/usr/local : Local hierarchy</A

>

<A

NAME="PURPOSE25" >Purpose</A

>

This directory contains any non-essential binaries used

exclusively by the system administrator. System administration programs that are required for system repair, system recovery, mounting /usr, or other essential functions must be placed in /sbin instead.

<A NAME="AEN1540" HREF="#FTN.AEN1540" >[29]</A

<A

NAME="PURPOSE26" >Purpose</A

>

The /usr/share hierarchy is for all

read-only architecture independent data files.

<A NAME="AEN1550" HREF="#FTN.AEN1550" >[30]</A

This hierarchy is intended to be shareable among all

architecture platforms of a given OS; thus, for example, a site with i386, Alpha, and PPC platforms might maintain a single /usr/share directory that is centrally-mounted. Note, however, that /usr/share is generally not intended to be shared by different OSes or by different releases of

Any program or package which contains or requires data that

doesn't need to be modified should store that data in /usr/share (or /usr/local/share, if installed locally). It is recommended that a subdirectory be used in

Game data stored in /usr/share/games must

be purely static data. Any modifiable files, such as score files, game play logs, and so forth, should be placed in

<A

NAME="REQUIREMENTS11" >Requirements</A

>

The following directories, or symbolic links to directories, must be in /usr/share

<A

NAME="SPECIFICOPTIONS15" >Specific Options</A

>

The following directories, or symbolic links to directories, must be in /usr/share, if the corresponding subsystem is installed:

It is recommended that application-specific,

architecture-independent directories be placed here. Such directories include groff, perl, ghostscript, texmf, and kbd (Linux) or syscons (BSD). They may, however, be placed in /usr/lib for backwards compatibility, at the distributor's discretion. Similarly, a /usr/lib/games hierarchy may be used in addition to the /usr/share/games hierarchy if

<A

NAME="USRSHAREDICTWORDLISTS" >/usr/share/dict : Word lists (optional)</A

>

<A

NAME="USRSHAREMANMANUALPAGES" >/usr/share/man : Manual pages</A

>

<A

NAME="USRSHAREMISCMISCELLANEOUSARCHITECTURE" >/usr/share/misc : Miscellaneous architecture-independent data</A

>

This directory contains miscellaneous architecture-independent

files which don't require a separate subdirectory under

<A

NAME="USRSHARESGMLSGMLANDXMLDATA" >/usr/share/sgml : SGML data (optional)</A

>

<A

NAME="AEN2007" >/usr/share/xml : XML data (optional)</A

>

<A

NAME="PURPOSE30" >Purpose</A

>

Source code may be place placed in this

subdirectory, only for reference purposes.

<A NAME="AEN2042" HREF="#FTN.AEN2042" >[35]</A

<A

NAME="PURPOSE32" >Purpose</A

>

This directory holds the current active process accounting log

and the composite process usage data (as used in some UNIX-like systems by lastcomm and

<A

NAME="PURPOSE33" >Purpose</A

>

/var/cache is intended for cached data from

applications. Such data is locally generated as a result of time-consuming I/O or calculation. The application must be able to regenerate or restore the data. Unlike /var/spool, the cached files can be deleted without data loss. The data must remain valid between invocations of

Files located under /var/cache may be

expired in an application specific manner, by the system administrator, or both. The application must always be able to recover from manual deletion of these files (generally because of a disk space shortage). No other requirements are made on the data

<A

NAME="SPECIFICOPTIONS21" >Specific Options</A

>

<A

NAME="VARCACHEFONTSLOCALLYGENERATEDFONTS" >/var/cache/fonts : Locally-generated fonts (optional)</A

>

<A

NAME="VARCACHEMANLOCALLYFORMATTEDMANUALPAG" >/var/cache/man : Locally-formatted manual pages (optional)</A

>

<A

NAME="PURPOSE36" >Purpose</A

>

This directory holds system crash dumps. As of the date of this

release of the standard, system crash dumps were not supported under Linux but may be supported by other systems which may comply with the

<A

NAME="PURPOSE37" >Purpose</A

>

Any variable data relating to games in /usr

should be placed here. /var/games should hold the variable data previously found in /usr; static data, such as help text, level descriptions, and so on, must remain elsewhere, such as

<A

NAME="PURPOSE38" >Purpose</A

>

This hierarchy holds state information pertaining to an

application or the system. State information is data that programs modify while they run, and that pertains to one specific host. Users must never need to modify files in /var/lib to

State information is generally used to preserve the condition of

an application (or a group of inter-related applications) between invocations and between different instances of the same application. State information should generally remain valid after a reboot, should

An application (or a group of inter-related applications) must

use a subdirectory of /var/lib for its data. There is one required subdirectory, /var/lib/misc, which is intended for state files that don't need a subdirectory; the other subdirectories should only be present if the application in question is included in the distribution.

<A NAME="AEN2295" HREF="#FTN.AEN2295" >[38]</A

/var/lib/<name> is the location that

must be used for all distribution packaging support. Different

<A

NAME="REQUIREMENTS13" >Requirements</A

>

The following directories, or symbolic links to directories, are required in /var/lib:

<A

NAME="SPECIFICOPTIONS23" >Specific Options</A

>

The following directories, or symbolic links to directories, must be in /var/lib, if the corresponding subsystem is installed:

<A

NAME="VARLIBLTEDITORGTEDITORBACKUPFILESAN" >/var/lib/<editor> : Editor backup files and state (optional)</A

>

<A

NAME="VARLIBHWCLOCKSTATEDIRECTORYFORHWCLO" >/var/lib/hwclock : State directory for hwclock (optional)</A

>

<A

NAME="VARLIBMISCMISCELLANEOUSVARIABLEDATA" >/var/lib/misc : Miscellaneous variable data</A

>

<A

NAME="PURPOSE42" >Purpose</A

>

Lock files should be stored within the /var/lock directory structure.

Lock files for devices and other resources shared by multiple

applications, such as the serial device lock files that were originally found in either /usr/spool/locks or /usr/spool/uucp, must now be stored in /var/lock. The naming convention which must be used is "LCK.." followed by the base name of the device. For example, to lock /dev/ttyS0 the file "LCK..ttyS0" would be created.

<A NAME="AEN2396" HREF="#FTN.AEN2396" >[40]</A

The format used for the contents of such lock files must be the

HDB UUCP lock file format. The HDB format is to store the process identifier (PID) as a ten byte ASCII decimal number, with a trailing newline. For example, if process 1230 holds a lock file, it would contain the eleven characters: space, space, space, space, space,

<A

NAME="PURPOSE43" >Purpose</A

>

This directory contains miscellaneous log files. Most logs must be written to this directory or an appropriate subdirectory.

<A

NAME="SPECIFICOPTIONS24" >Specific Options</A

>

The following files, or symbolic links to files, must be in

/var/log, if the corresponding subsystem is

<A

NAME="PURPOSE44" >Purpose</A

>

The mail spool must be accessible through

/var/mail and the mail spool files must take the form <username>. <A NAME="AEN2437" HREF="#FTN.AEN2437" >[41]</A

User mailbox files in this location must be stored in the standard UNIX mailbox format.

<A

NAME="PURPOSE45" >Purpose</A

>

Variable data of the packages in /opt must

be installed in /var/opt/<subdir>, where <subdir> is the name of the subtree in /opt where the static data from an add-on software package is stored, except where superseded by another file in /etc. No structure is imposed on the internal

<A

NAME="PURPOSE46" >Purpose</A

>

This directory contains system information data describing the

system since it was booted. Files under this directory must be cleared (removed or truncated as appropriate) at the beginning of the boot process. Programs may have a subdirectory of /var/run; this is encouraged for programs that use more than one run-time file.

<A NAME="AEN2469" HREF="#FTN.AEN2469" >[42]</A >

Process identifier (PID) files, which were originally placed in /etc, must be placed in /var/run. The naming convention for PID files is <program-name>.pid. For example, the crond PID file is named

<A

NAME="REQUIREMENTS14" >Requirements</A

>

The internal format of PID files remains unchanged. The file

must consist of the process identifier in ASCII-encoded decimal, followed by a newline character. For example, if crond was process number 25, /var/run/crond.pid would contain three

Programs that read PID files should be somewhat flexible in what

they accept; i.e., they should ignore extra whitespace, leading zeroes, absence of the trailing newline, or additional lines in the PID file. Programs that create PID files should use the simple

The utmp file, which stores information

about who is currently using the system, is located in this

System programs that maintain transient UNIX-domain sockets must place them in this directory.

<A

NAME="PURPOSE47" >Purpose</A

>

/var/spool contains data which is awaiting

some kind of later processing. Data in /var/spool represents work to be done in the future (by a program, user, or administrator); often data is deleted after it has been processed.

<A NAME="AEN2493" HREF="#FTN.AEN2493" >[43]</A

<A

NAME="SPECIFICOPTIONS25" >Specific Options</A

>

The following directories, or symbolic links to directories,

must be in /var/spool, if the corresponding

<A

NAME="VARSPOOLLPDLINEPRINTERDAEMONPRINTQU" >/var/spool/lpd : Line-printer daemon print queues (optional)</A

>

<A

NAME="VARSPOOLRWHORWHODFILES" >/var/spool/rwho : Rwhod files (optional)</A

>

<A

NAME="PURPOSE50" >Purpose</A

>

The /var/tmp directory is made available

for programs that require temporary files or directories that are preserved between system reboots. Therefore, data stored in /var/tmp is more persistent than data in

Files and directories located in /var/tmp

must not be deleted when the system is booted. Although data stored in /var/tmp is typically deleted in a site-specific manner, it is recommended that deletions occur at a less

<A

NAME="PURPOSE51" >Purpose</A

>

Variable data for the Network Information Service (NIS),

formerly known as the Sun Yellow Pages (YP), must be placed in this

<A

NAME="ROOTDIRECTORY" >/ : Root directory</A

>

On Linux systems, if the kernel is located in

/, we recommend using the names vmlinux or vmlinuz, which

<A

NAME="BINESSENTIALUSERCOMMANDBINARIES2" >/bin : Essential user command binaries (for use by all users)</A

>

Linux systems which require them place these additional files into /bin:

• setserial

<A

NAME="DEVDEVICESANDSPECIALFILES" >/dev : Devices and special files</A

>

The following devices must exist under /dev.

<P

<A

NAME="ETCHOSTSPECIFICSYSTEMCONFIGURATION2" >/etc : Host-specific system configuration</A

>

Linux systems which require them place these additional files into /etc.

• lilo.conf

<A

NAME="LIB64" >/lib64 and /lib32 : 64/32-bit libraries (architecture dependent)</A

>

&#13;The 64-bit architectures PPC64, s390x, sparc64 and AMD64 must place

64-bit libraries in /lib64, and 32-bit

The 64-bit architecture IA64 must place 64-bit libraries in

/lib.

<A

NAME="PROCKERNELANDPROCESSINFORMATIONVIR" >/proc : Kernel and process information virtual filesystem</A

>

The proc filesystem is the de-facto

standard Linux method for handling process and system information, rather than /dev/kmem and other similar methods. We strongly encourage this for the storage and retrieval of process

<A

NAME="SBINESSENTIALSYSTEMBINARIES" >/sbin : Essential system binaries</A

>

Linux systems place these additional files into /sbin.

• Second extended filesystem commands (optional):

  • badblocks

  • dumpe2fs

  • e2fsck

  • mke2fs

  • mklost+found

  • tune2fs

• Boot-loader map installer (optional):

  • lilo

Optional files for /sbin:

• Static binaries:

  • ldconfig

  • sln

  • ssync

  Static ln (sln) and

  static sync (ssync) are useful when things go wrong. The primary use of sln (to repair incorrect symlinks in /lib after a poorly orchestrated upgrade) is no longer a major concern now that the ldconfig program (usually located in /usr/sbin) exists and can act as a guiding hand in upgrading the dynamic libraries. Static sync is useful in some emergency situations. Note that these need not be statically linked versions of the standard ln and sync, but may

  be.

  The ldconfig binary is optional for

  /sbin since a site may choose to run ldconfig at boot time, rather than only when upgrading the shared libraries. (It's not clear whether or not it is advantageous to run ldconfig on each boot.) Even so, some people like ldconfig around for the

  following (all too common) situation:

  1. I've just removed /lib/<file>.

  2. I can't find out the name of the library because ls is

     dynamically linked, I'm using a shell that doesn't have ls built-in, and I don't know about using "echo *" as a

     replacement.

  3. I have a static sln, but I don't know what to call the link.

• Miscellaneous:

  • ctrlaltdel

  • kbdrate

  So as to cope with the fact that some keyboards come up with

  such a high repeat rate as to be unusable, kbdrate may be installed in

  /sbin on some systems.

  Since the default action in the kernel for the Ctrl-Alt-Del key

  combination is an instant hard reboot, it is generally advisable to disable the behavior before mounting the root filesystem in read-write mode. Some init suites are able to disable Ctrl-Alt-Del, but others may require the ctrlaltdel program, which may be installed in

  /sbin on those systems.

<A

NAME="USRINCLUDEHEADERFILESINCLUDEDBYCP" >/usr/include : Header files included by C programs</A

>

These symbolic links are required if a C or C++ compiler is installed and only for systems not based on glibc.

    /usr/include/asm -> /usr/src/linux/include/asm-<arch>
    /usr/include/linux -> /usr/src/linux/include/linux

<A

NAME="USRSRCSOURCECODE2" >/usr/src : Source code</A

>

For systems based on glibc, there are no specific guidelines for

this directory. For systems based on Linux libc revisions prior to

The only source code that should be placed in a specific

location is the Linux kernel source code. It is located in

If a C or C++ compiler is installed, but the complete Linux

kernel source code is not installed, then the include files from the

    /usr/src/linux/include/asm-<arch>
    /usr/src/linux/include/linux

<arch> is the name of the system architecture.

<A

NAME="VARSPOOLCRONCRONANDATJOBS" >/var/spool/cron : cron and at jobs</A

>

This directory contains the variable data for the cron and at programs.