Man auto master

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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,nosuid
           /home                   auto_home       -nobrowse
           /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 distinct from nobrowse used as a Mac OS X mount option, which
     affects the visibility of the mount to the Finder.

     A map name beginning with / is the pathname of a file containing the map, otherwise the name repre-
     sents a map to be found as a file in /etc or to be read from Directory Services.

     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

           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 sin-
     gle map entry.

     The location can be preceded by a comma-separated list of mount options with a prepended ``-''.  For

             bin     -ro,nosuid  mynfs:/export/bin

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 direc-
     tory.  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 enumer-
     ate map keys for a directory listing, it invokes the map with no arguments and expects a newline-
     separated list of keys on stdout.  For example:

             if [ $# = 0 ]; then # List keys
                     ypcat -k auto_entries | awk '{print $1}'
             # Return location
             ypmatch $1 auto_entries

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

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

     -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

                   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

     /etc/auto_master  The master map file.

     automount(8), automountd(8), autofsd(8), autofs.conf(5)

Darwin                          April 20, 2007                          Darwin

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