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

NAME

     auto_master -- automounter master map

DESCRIPTION

     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 mas-
     ter map is distinct 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
	   +auto_master

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

AUTOMOUNTER MAPS

     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 backslash 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 example:

	   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
     chosen.  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 shortest response time to the aforementioned NFS null request will be cho-
     sen.  A location can be given a weighting factor; the higher the weighting factor, 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 followed 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 associated 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 auto-
     mounter 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

	   #!/bin/sh
	   if [ $# = 0 ]; then # List keys
		   dscl /Search -list Users
		   exit
	   fi
	   # 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
			   ;;
		   esac
		   ;;

	   "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
		   ;;
	   esac

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

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 exam-
     ple, a map entry of

	   bill    argon:/export/home/&

     is equivalent to a map entry of

	   bill    argon:/export/home/bill

Wildcards
     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 with

	   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}.

Variables
     A location string in a map can contain references to variables.  A reference 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 characters 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 PowerPC 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 containing 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.

Quoting
     Special characters, such as white space characters, a dollar sign, or an ampersand can be quoted by escaping them with a backslash (); this
     prevents white space from being interpreted as a field separator, prevents a dollar sign from being interpreted as the beginning of a vari-
     able 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 spec-
		   ify 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 /net.

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

			 /shared	 -null
			 +auto_master

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

     -static	   This map is a direct map, so the mount point must be specified 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

FILES

     /etc/auto_master  The master map file.

SEE ALSO

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

Darwin								  April 20, 2007							    Darwin