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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 begin-ning beginning
     ning 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 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 fold-ers folders
     ers 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 exam-ple: example:
     ple:

           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 afore-mentioned aforementioned
     mentioned NFS null request will be chosen.  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 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

           #!/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 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

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 prede-fined predefined
     fined 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 spa-ces spaces
                   ces 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 appro-priate appropriate
     priate 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 separa-tor, separator,
     tor, 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 speci-fied specified
                   fied 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 equiva-lent equivalent
                   lent 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 asso-ciated associated
                   ciated 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