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AUTO_MASTER(5)		    BSD File Formats Manual		AUTO_MASTER(5)

     auto_master — automounter master map

     The auto_master file contains a list of the directories that are to be
     automounted.  Associated with each directory is the name of a map that
     lists the locations of the filesystems to be automounted there.  The
     default map looks like this:

	   # Automounter master map
	   +auto_master		   # Use directory service
	   /net			   -hosts	   -nobrowse,hidefromfinder,nosuid
	   /home		   auto_home	   -nobrowse,hidefromfinder
	   /Network/Servers	   -fstab
	   /-			   -static

     A “#” is the comment character. All characters from it to the end of line
     are ignored.  A line beginning with “+” and followed by a name, indicates
     the name of a file or map accessible from a Directory Service source such
     as NIS or LDAP; the master map entries in that file or map are included
     at this point in the master map.  A line that specifies a map to be
     mounted has the format:

	   mountpoint map -options

     where mountpoint is the directory on which the map is to be mounted, map
     is the name of the map to be mounted, and options is an optional, comma-
     separated list of default mount options to be used by any entries in the
     map that do not have their own mount options.  The nobrowse option is
     used on maps that have the potential to produce entries too numerous for
     browsing to be practical. This option as used in the master map is dis‐
     tinct from nobrowse used as a Mac OS X mount option, which affects the
     visibility of the mount to the Finder.  The hidefromfinder option is used
     on maps that shouldn't show up as folders in the Finder; it causes the
     UF_HIDDEN flag to be set on the root directory of the map.

     A map name beginning with / is the pathname of a file containing the map,
     otherwise the name represents a map to be found as a file in /etc or to
     be read from Directory Service (and thus from whatever sources Directory
     Service uses, such as NIS or LDAP servers).

     Note that, in order to get automounter maps from NIS, the "BSD Flat File
     and NIS" plugin must, in the Directory Utility application, be enabled
     and configured to "Use NIS domain for authentication".

     If more than one entry in the master map has the same mountpoint then all
     but the first are ignored.	 For instance, in the following master map:

	   /shared	   my_auto_shared

     The /shared entry overrides any /shared specification imported from the
     network auto_master.

     Automounter maps associate directories with the locations of filesystems
     that are to be mounted when the directory is accessed.  Map entries have
     the general form:

	   key location

     These map entries may be represented by lines in a file, NIS or LDAP
     tables indexed by the key, or from output of an executable map.  Most
     commonly, the location is simply the name of an NFS server and the path
     to an exported file system, e.g.

	   local   mynfs:/export/local

     A location can also represent multiple mounts, where each is associated
     with a relative path, for example:

	   pkg	   \
		   /data   mynfs:/export/pkg/data \
		   /bin	   mynfs:/export/pkg/bin  \
		   /man	   mynfs:/export/pkg/man

     Reference to this entry will provide access to any of three exported file
     systems from the server, each via its own subdirectory.  Each of these
     sub-mounts will be done only when referenced.  Note the use of a back‐
     slash to escape the newline so that the automounter will read these lines
     as a single map entry.

     The location can be preceded by a comma-separated list of mount options
     with a prepended “-”.  For example:

	   bin	   -ro,nosuid  mynfs:/export/bin

     For file system types other than NFS, the mount option -fstype=⟨type⟩ can
     be used to specify the file system type.  The location would be in the
     form expected by the mount command for that file system type.  For exam‐

	   smb	   -fstype=smb //guest@smbserver/share
	   afp	   -fstype=afp afp://;AUTH=NO%20USER%20AUTHENT@afpserver/share

     If the location is a URL, with a scheme specifying AFP, NFS, or SMB,
     then, if no file system type is specified, the directory referred to by
     that URL will be mounted using mount_url(8).  For example:

	   nfsurl  nfs://nfsserver/path/to/mount
	   smburl  smb://guest@smbserver/share
	   afpurl  afp://;AUTH=NO%20USER%20AUTHENT@afpserver/share

Replicated mounts
     More than one location can be specified in a map entry.  At the time the
     mount is done, the automounter will choose one of those locations to
     mount.  Locations not responding to an NFS null request at that time will
     not be considered, so that servers that are unavailable will not be cho‐
     sen.  Servers that are on the same subnet as the client will be chosen in
     preference to servers on different subnets.

     By default, in each of those sets of servers, the server with the short‐
     est response time to the aforementioned NFS null request will be chosen.
     A location can be given a weighting factor; the higher the weighting fac‐
     tor, the lower the preference for that server.  For example, with an
     entry such as

	   data	   net1a:/data net1b:/data net1c(1):/otherdata

     if either host net1a or net1b is available, the one with the shortest
     response time will be chosen; host net1c will be chosen only if it is
     available and neither hosts net1a nor net1b are available.

     If all locations have the same path, a comma-separated list of hosts fol‐
     lowed by the path can be used:

	   data	   net1a,net1b,net1c(1):/data

     If a server that has been mounted becomes unavailable, the NFS client
     will not automatically fail over to another server; the mount must be
     unmounted and remounted in order for failover to occur.

Direct Map
     A direct map associates filesystem locations directly with directories.
     The entry key is the full path name of a directory.  For example:

	   /usr/local	   eng4:/export/local
	   /src		   eng4:/export/src

     Since the direct map as a whole isn't associated with a single directory,
     it is specified in the master map with a dummy directory name of /-.

Indirect Map
     An indirect map is used where a large number of entries are to be associ‐
     ated with a single directory.  Each map entry key is the simple name of a
     directory entry.  A good example of this is the auto_home map which
     determines the entries under the /home directory.	For example:

	   bill	   argon:/export/home/bill
	   brent   depot:/export/home/brent
	   guy	   depot:/export/home/guy

Executable Map
     An executable map is an indirect map represented by a file that has its
     execute bit set.  Instead of reading entries from the file directly, the
     automounter executes the program or script passing the key as an argument
     and receiving the location string on stdout.  If the automounter needs to
     enumerate map keys for a directory listing, it invokes the map with no
     arguments and expects a newline-separated list of keys on stdout.

     If an error occurs, the executable map must return a non-zero exit status
     and no output.

     For example, a map that, when bound to an Open Directory server, has one
     entry for every user, with the key being the user's login name and the
     entry being the URL of the user's home directory, could be implemented as

	   if [ $# = 0 ]; then # List keys
		   dscl /Search -list Users
	   # Return location
	   homedirloc=`dscl /Search -read Users/$1 HomeDirectory`
	   case "$homedirloc" in

	   "No such key: HomeDirectory"*)
		   homedirloc=`dscl /Search -read Users/$1 NFSHomeDirectory`
		   case "$homedirloc" in

		   "NFSHomeDirectory: /Network/Servers/"*)
			   # NFS home directory
			   echo "$homedirloc" | sed 's;NFSHomeDirectory: /Network/Servers//]*/;1:/2;'

			   # Unknown
			   exit 1

	   "HomeDirectory: <home_dir><url>smb://"*)
		   # SMB home directory
		   echo "$homedirloc" | sed -e 's;HomeDirectory: <home_dir><url>;;' -e 's;</url><path>;/;' -e 's;</path></home_dir>;;'

		   # Unknown
		   exit 1

     (this is a simplified example; it does not handle users who do not have a
     network home directory, but includes them in the directory listing).

Substituting the map key entry
     If a location in a map entry contains an ampersand (&), the ampersand
     will be replaced by the value of the key for the map entry.  For example,
     a map entry of

	   bill	   argon:/export/home/&

     is equivalent to a map entry of

	   bill	   argon:/export/home/bill

     If the key in an indirect map entry is an asterisk (*), that entry will
     match any name that isn't matched by any other entry.  For example, a map

	   bill	   argon:/export/home/bill
	   *	   depot:/export/home/&

     as entries will mount argon:/export/home/bill on bill and will mount
     depot:/export/home/{user} on {user} for all other values of {user}.

     A location string in a map can contain references to variables.  A refer‐
     ence to a variable consists of dollar sign ($) followed by the name of
     the variable.  A variable name is a sequence of alphanumeric characters
     and underscores; the name of the variable can be contained in curly
     braces to separate the variable reference from any alphanumeric charac‐
     ters or underscores following it.	There are some predefined variables:

	   ARCH	   System architecture ("macintosh" on Macintoshes).

	   CPU	   Processor type, as reported by uname -p ("powerpc" on Pow‐
		   erPC Macintoshes, "i386" on Intel Macintoshes).

	   HOST	   This machine's host name.

	   OSNAME  Operating system name, as reported by uname -s ("Darwin" in
		   OS X).

	   OSREL   Operating system release, as reported by uname -r (for
		   example, 9.3.0 in Mac OS X 10.5.3).

	   OSVERS  Operating system version, as reported by uname -v (this
		   string is a long string with spaces in Mac OS X, and is not
		   very useful in automounter maps).

     For example, a direct map entry such as

	   /usr/local/bin  -ro	   server:/export/bin/$OSNAME/$CPU

     would mount on /usr/local/bin a directory from the specified server con‐
     taining executable images appropriate to the operating system and CPU
     type of the machine.

     In addition, any environment variable set in the environment of
     automountd(8) can be used as a variable name; those variables can be set
     with the AUTOMOUNTD_ENV parameter in the autofs.conf(5) file.

     Special characters, such as white space characters, a dollar sign, or an
     ampersand can be quoted by escaping them with a backslash (\); this pre‐
     vents white space from being interpreted as a field separator, prevents a
     dollar sign from being interpreted as the beginning of a variable name,
     and prevents an ampersand from being interpreted as the key field for the
     entry in which it occurs.	A sequence of characters can also be quoted by
     enclosing it in double-quotes (").

Special Maps
     The special maps have reserved names and are built into the automounter.

     -fstab	   This map would normally be mounted on /Network/Servers.
		   The key is the host name of a server; the contents of the
		   map entry are generated from corresponding entries in
		   fstab(5) data (as provided by getfsent(3)) that have the
		   net option and that specify mounts from that server.	 An
		   entry of the form

			 server:/path mountpoint fstype options 0 0

		   will be mounted in server/path under the mount point of the
		   -fstab map, using the specified fstype file system type and
		   the specified options.  The mountpoint is ignored.

     -hosts	   This map would normally be mounted on /net.	The key is the
		   host name of an NFS server; the contents of the map are
		   generated from the list of file systems exported by that
		   server.  For example, a server that exports three NFS
		   filesystems might have an equivalent map entry of:

			 myserv	 \
				 /export/home	 myserv:/export/home \
				 /export/local	 myserv:/export/local \
				 /export/pkg	 myserv:/export/pkg

		   To access the first mount, the path would be
		   /net/myserv/export/home if the map was associated with

     -null	   This map has no entries.  It is used to disable entries
		   that occur later in the auto_master file.  For example:

			 /shared	 -null

		   The -null entry disables any /shared entry in +auto_master.

     -static	   This map is a direct map, so the mount point must be speci‐
		   fied as /-.	The contents are generated from all entries in
		   fstab(5) data (as provided by getfsent(3)) that do not have
		   the net option.  An fstab(5) entry of the form

			 server:/path mountpoint fstype options rw 0 0

		   will generate a direct map entry of the form

			 mountpoint options server:/path

     /etc/auto_master  The master map file.

     automount(8), automountd(8), autofsd(8), autofs.conf(5), fstab(5),
     getfsent(3), DirectoryService(8)

Darwin				April 20, 2007				Darwin

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