Man auto master
From OS X Scientific Computing
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,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
+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 sin-
gle 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
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:
#!/bin/sh
if [ $# = 0 ]; then # List keys
ypcat -k auto_entries | awk '{print $1}'
exit
fi
# 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
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)
Darwin April 20, 2007 Darwin
Back to NFS on OS X 10.5
