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NAME    [Toc]    [Back]

     automount - automatically mount NFS filesystems

SYNOPSIS    [Toc]    [Back]

     /usr/etc/automount	[ -mnTv	] [ -D name=value ] [ -f master-file ] [ -p
     priority ]	[ -M mount-directory ] [ -tl duration ]	[ -tm interval ] [ -tp
     duration ]	[ -tw interval ] [ directory mapname [ -mount-options ]	] ...

DESCRIPTION    [Toc]    [Back]

     Automount is a daemon that	automatically and transparently	mounts NFS
     filesystems as needed. Whenever a user on a client	machine	running
     automount invokes a command that needs to access a	remote file or
     directory,	the hierarchy to which that file or directory belongs is
     mounted and remains mounted for as	long as	it is needed. When a certain
     amount of time has	elapsed	during which the hierarchy is not accessed, it
     is	automatically unmounted.  No mounting of unaccessed remote filesystems
     is	done at	boot-time, and the user	doesn't	need special privilege to
     mount a directory.

     The automount daemon is started during system initialization from the
     /etc/init.d/network script	if the configuration flags ``nfs'' and
     ``automount'' are set ``on.''  Do the following commands as super-user to
     enable automount:

	  /etc/chkconfig nfs on
	  /etc/chkconfig automount on

     Rebooting will start automount with the options and arguments contained
     in	the file /etc/config/automount.options.	 The default version of	this
     file lets you access exported directories on another host with the
     filename prefix of


     For example, if host springfield exports /usr, then

	  ls /hosts/springfield/usr

     will show the contents of that directory.	You may	want to	customize this
     file for your site.

     Unlike mount, automount does not consult the file /etc/fstab for a	list
     of	hierarchies to mount.  Rather, it consults a series of maps, which can
     be	either direct or indirect.  The	names of the maps can be passed	to
     automount from the	command	line (via the /etc/config/automount.options
     file), or from another (master) map.

     The master	map lists (as if from the command line)	all other maps,
     applicable	options, and mount points.

									Page 1


     An	indirect map allows you	to specify mappings for	the subdirectories you
     wish to mount under the directory indicated on the	command	line. In an
     indirect map, each	directory field	consists of the	basename of a
     subdirectory to be	mounted	as needed.

     A direct map contains mappings for	any number of directories.  Each
     directory listed in the map is automatically mounted as needed.  The
     direct map	as a whole is not associated with any single directory.

     automount appears to be an	NFS server to the kernel.  automount uses the
     map contained in the mapname argument to locate an	appropriate NFS	file
     server, exported filesystem, and mount options.  It then mounts the
     filesystem	in a temporary location, and creates a symbolic	link to	the
     temporary location.  If the filesystem is not accessed within an
     appropriate interval (five	minutes	by default), the daemon	unmounts the
     filesystem	and removes the	symbolic link.	If the indicated directory has
     not already been created, the daemon creates it, and then removes it upon

     By	default, automount mounts everything under the directory /tmp_mnt.
     For instance, if a	user wants to mount a remote directory src under
     /usr/src, the actual mount	point will be /tmp_mnt/usr/src,	and /usr/src
     will be a symbolic	link to	that location.

     As	with any other kind of mount, a	mount effected through the automounter
     on	a non-empty mount point	will hide the original contents	of the mount
     point for as long as the mount is in effect.

     Since the name-to-location	binding	is dynamic, updates to an automount
     map are transparent to the	user.  This obviates the need to ``pre-mount''
     shared file systems for applications that have ``hard-coded'' references
     to	files.	Nor is there a need to maintain	records	of which hosts must be
     mounted for what applications.

     If	the directory argument is a pathname, the map argument points to an
     indirect map.  An indirect	map contains a list of the subdirectories
     contained within the indicated directory.	With an	indirect map, it is
     these subdirectories that are mounted automatically.

     If	the directory argument is `/-',	automount treats the map argument that
     follows as	the name of a direct map.  In a	direct map, each entry
     associates	the full pathname of a mount point with	a remote filesystem to

     A map can be a file or a network information service (NIS)	map; if	a
     file, the map argument must be a full pathname.

     The -mount-options	argument, when supplied, consists of the leading dash
     and a comma-separated list	of options to mount(1M), as described in
     fstab(4).	If these options are supplied, they become the default mount
     options for all entries in	the map.  Mount	options	provided within	a map
     entry override these defaults.

									Page 2


OPTIONS    [Toc]    [Back]

     -D	var=value
	  Assign value to the indicated	automount (environment)	variable.

     -f	 master-file
	  Read a local file for	initialization,	before reading the auto.master
	  NIS map.  The	information in master-file will	take precedence.

     -m	  Suppress initialization of directory-mapname pairs listed in the
	  auto.master NIS database.

     -M	 mount-directory
	  Mount	temporary filesystems in the named directory, instead of

     -n	  Disable dynamic mounts.  With	this option, references	through	the
	  automount daemon only	succeed	when the target	filesystem has been
	  previously mounted.  This can	be used	to prevent NFS servers from
	  cross-mounting each other.

     -T	  Trace.  Expand each NFS call and display it on standard error.

     -p	 priority
	  Set the (non-degrading) priority of the automount process.  The
	  default is NDPNORMAX (40).

     -tl  duration
	  Specify a duration, in seconds, that a filesystem is to remain
	  mounted when not in use.  The	default	is 300 seconds (5 minutes).

     -tm  interval
	  Specify an interval, in seconds, between attempts to mount a
	  filesystem.  The default is 30 seconds.

     -tp  duration
	  Specify the duration,	in seconds, that the results of	a probe	of a
	  server's availability	will remain cached.  The default is 5 seconds.

     -tw  interval
	  Specify an interval, in seconds, between attempts to unmount
	  filesystems that have	exceeded their cached times.  The default is
	  60 seconds.

     -v	  Verbose.  Log	status and/or warning messages through syslog(3B) or
	  to the console.

ENVIRONMENT    [Toc]    [Back]

     Environment variables can be used within an automount map.	 For instance,
     if	$HOME appeared within a	map, automount would expand it to its current
     value for the HOME	variable.  Environment variables are expanded only for
     the automounter's environment - not for the environment of	a user using
     the automounter's services.

									Page 3


     If	a variable reference needs to be protected from	affixed	characters,
     you can surround the variable name	with curly braces.

USAGE    [Toc]    [Back]

   Map Entry Format
     A simple map entry	(mapping) takes	the form:

	  directory [ -mount-options ] location	...

     where directory is	the full pathname of the directory to mount when used
     in	a direct map, or the basename of a subdirectory	in an indirect map.
     mount-options is a	comma-separated	list of	options	to mount(1M), as
     described in fstab(4), and	location specifies a remote filesystem from
     which the directory may be	mounted.  In the simple	case, location takes
     the form:


   Replicated Filesystems
     Multiple location fields can be specified for replicated read-only
     filesystems, in which case	automount sends	multiple mount requests;
     automount mounts the filesystem from the first host that replies to the
     mount request.  This request is first made	to the local net or subnet.
     If	there is no response, any connected server may respond.	 Since
     automount does not	monitor	the status of the server while the filesystem
     is	mounted, it will not use another location in the list if the currently
     mounted server crashes.  This support for replicated filesystems is
     available only at mount time.  Once unmounted, another location may be
     used for subsequent mounts	of the filesystem.

     If	each location in the list shares the same pathname then	a single
     location may be used with a comma-separated list of hostnames:


   Sharing Mounts
     If	location is specified in the form:


     hostname is the name of the server	from which to mount the	filesystem,
     pathname is the pathname of the directory to mount, and subdir, when
     supplied, is the name of a	subdirectory to	which the symbolic link	is
     made.  This can be	used to	prevent	duplicate mounts when multiple
     directories in the	same remote filesystem may be accessed.	 With an
     indirect map for /home such as:

	  bart	    springfield:/home/simpsons:bart
	  maggie	 springfield:/home/simpsons:maggie

     and a user	attempting to access a file in /home/bart, automount mounts
     springfield:/home/simpsons, but creates a symbolic	link called /home/bart

									Page 4


     to	the bart subdirectory in the temporarily-mounted filesystem.  If a
     user immediately tries to access a	file in	/home/maggie, automount	needs
     only to create a symbolic link that points	to the maggie subdirectory;
     /home/simpsons is already mounted.

     With the following	map:

	  bart		 springfield:/home/simpsons/bart
	  maggie	 springfield:/home/simpsons/maggie

     automount would have to mount the filesystem twice.

   Comments and	Quoting
     A mapping can be continued	across input lines by escaping the NEWLINE
     with a backslash.	Comments begin with a #	and end	at the subsequent

     Characters	that have special significance to the automount	map parser may
     be	protected either with double quotes (")	or by escaping with a
     backslash (\).  Pathnames with embedded whitespace, colons	(:) or dollars
     ($) should	be protected.

   Directory Pattern Matching
     The `&' character is expanded to the value	of the directory field for the
     entry in which it occurs.	In this	case:

	  bart springfield:/home/simpsons:&

     the & expands to bart.  The `*' character,	when supplied as the directory
     field, is recognized as the catch-all entry.  Such	an entry will be used
     if	any previous entry has not successfully	matched	the key	being searched
     for.  For instance, if the	following entry	appeared in the	indirect map
     for /home:

	  *    &:/home/&

     this would	allow automatic	mounts in /home	of any remote filesystem whose
     location could be specified as:


   Multiple Mounts
     A multiple	mount entry takes the form:

	  directory [ /[ subdirectory [	-mount-options ] location ... ]	...

     The initial / preceding the subdirectory is required; the optional
     subdirectory is taken as a	pathname relative to the directory.  If
     subdirectory is omitted in	the first occurrence, the / refers to the
     directory itself.

									Page 5


     Given the direct map entry:

	  /tools \
	     /	       -ro  dill:/tools		 mint:/tools \
	     /1.0      -ro  mint:/tools/1.0	 dill:/tools/1.0 \
	     /1.0/man  -ro  dill:/tools/1.0/man	 mint:/tools/1.0/man

     automount would automatically mount /tools, /tools/1.0 and
     /tools/1.0/man, as	needed,	from either dill or mint, whichever host
     responded first.  If the mounts are hierarchically	related, mounts	closer
     to	the root must appear before submounts.	All the	mounts of a multiple
     mount entry will occur together and will be unmounted together.  This is
     important if the filesystems reference each other with relative symbolic
     links.  Multiple mount entries can	be used	both in	direct maps and	in
     indirect maps.

   Included Maps    [Toc]    [Back]
     The contents of another map can be	included within	a map with an entry of
     the form:


     mapname can either	be a filename, or the name of an NIS map, or one of
     the special maps described	below.	If the directory being searched	for is
     not located in an included	map, the search	continues with the next	entry.

   Special Maps    [Toc]    [Back]
     There are two special maps	currently available:  -hosts and -null.	 The
     -hosts map	uses the NIS hosts.byname map to locate	a remote host when the
     hostname is specified.  This map specifies	mounts of all exported
     filesystems from any host.	 For instance, if the following	automount
     command is	already	in effect:

	  automount  /hosts  -hosts

     then a reference to /hosts/springfield/usr	would initiate an automatic
     mount of all filesystems from springfield that automount can mount;
     references	to a directory under /hosts/springfield	will refer to the
     corresponding directory relative to springfield's root.

     The -null map, when indicated on the command line,	cancels	any subsequent
     map for the directory indicated.  It can be used to cancel	a map given in
     auto.master or for	a mount	point specified	as an entry in a direct	map.

   Configuration and the auto.master Map    [Toc]    [Back]
     automount normally	consults the auto.master NIS configuration map for a
     list of initial automount maps, and sets up automatic mounts for them in
     addition to those given on	the command line.  If there are	duplications,
     the command-line arguments	take precedence	over a local -f	master map and
     they both take precedence over an NIS auto.master map.  This
     configuration database contains arguments to the automount	command,
     rather than mappings; unless -f is	in effect, automount does not look for

									Page 6


     an	auto.master file on the	local host.

     Maps given	on the command line, or	those given in a local auto.master
     file specified with -f override those in the NIS auto.master map.	For
     instance, given the command:

	  automount -f /etc/auto.master	/home -null /- /etc/auto.direct

     and a file	named /etc/auto.master that contains:

	  /homes  auto.home

     automount would mount home	directories under /homes instead of /home, in
     addition to the various directories specified in the /etc/auto.direct

FILES    [Toc]    [Back]

	  directory under which	filesystems are	dynamically mounted

	  site-dependent options and arguments

SEE ALSO    [Toc]    [Back]

     mount(1M),	network(1M), chkconfig(1M), fstab(4), exports(4), schedctl(2)

NOTES    [Toc]    [Back]

     The -hosts	map mounts all of the exported filesystems, for	which the
     client has	access,	from a server. Use of the nohide export	option on the
     server (see exports(4)) may be used to minimize the number	of mounts
     performed by clients. Automount will not request a	separate mount for a
     nohide filesystem,	if the client has access via the parent	filesystem.
     If	frequent access	to just	a single filesystem is required, it is more
     efficient to access the filesystem	with a map entry that is tailored to
     mount just	the filesystem of interest.

     When it receives signal number 1, SIGHUP, automount rereads the /etc/mtab
     file to update its	internal record	of currently-mounted filesystems.  If
     a filesystem mounted with automount is unmounted with the umount(1M)
     command, automount	should be forced to reread the file by using the

	  /etc/killall -HUP automount

     An	ls(1) listing of the entries in	the directory for an indirect map
     shows only	the symbolic links for currently mounted filesystems.  This
     restriction is intended to	avoid unnecessary mounts as a side effect of
     programs that read	the directory and stat(2) each of the names.

     Mount points for a	single automounter must	not be hierarchically related.
     automount will not	allow an automount mount point to be created within an
     automounted filesystem.

									Page 7


     The recommended way to terminate automount	services is to send a SIGTERM
     signal to the daemon:

	  /etc/killall -TERM automount

     This allows the automounter to catch the signal and unmount not only its
     daemon but	also any mounts	in /tmp_mnt.  Mounts in	/tmp_mnt that are busy
     will not be unmounted.  automount must not	be terminated with the SIGKILL
     signal.  Without an opportunity to	unmount	itself,	the automount mount
     points will appear	to the kernel to belong	to a non-responding NFS

     Since each	direct map entry results in a separate mount for the mount
     daemon, such maps should be kept short.  Although both direct and
     indirect maps can be modified at any time,	entries	added to a direct map
     will have no effect until the automounter is restarted.

     Automount mount points are	mounted	with type ignore; they do not appear
     in	the output of either mount(1M) or df(1).  Automatically-mounted
     filesystems, on the other hand, are mounted with type nfs and are
     reported along with other NFS-mounted filesystems.

BUGS    [Toc]    [Back]

     Shell filename expansion does not apply to	objects	not currently mounted.

     The bg mount option is not	recognized by the automounter.

     Since automount is	single-threaded, any request that is delayed by	a slow
     or	non-responding NFS server will delay all subsequent automatic mount
     requests until it completes.

     Programs that read	/etc/mtab and then touch files that reside under
     automatic mount points will introduce further entries to the file.

									PPPPaaaaggggeeee 8888
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