NAME
auto_master —
auto_master and map file
format
DESCRIPTION
The automounter configuration consists of the
auto_master
configuration file, which assigns file system paths to map names, and maps,
which contain actual mount information. The
auto_master
configuration file is used by the
automount(8) command. Map
files are read by the
automountd(8) daemon.
AUTO_MASTER SYNTAX
The
auto_master file consists of lines with two or three
entries separated by whitespace and terminated by a newline character:
mountpoint map_name [-options]
mountpoint is either a fully specified path, or
/-. When
mountpoint is a full path,
map_name must reference an indirect map. Otherwise,
map_name must reference a direct map. See
MAP SYNTAX below.
map_name specifies map to use. If
map_name begins with
-
, it
specifies a special map. See
MAP SYNTAX
below. If
map_name is not a fully specified path (it
does not start with
/
),
automountd(8) will search
for that name in
/etc. Otherwise it will use the path as
given. If the file indicated by
map_name is executable,
automountd(8) will assume it
is an executable map. See
MAP SYNTAX
below. Otherwise, the file is opened and the contents parsed.
[
-options] is an
optional field that starts with
- and can contain generic
file system mount options.
The following example specifies that the
/etc/auto_example
indirect map will be mounted on
/example.
MAP SYNTAX
Map files consist of lines with a number of entries separated by whitespace and
terminated by newline character:
key [-options] [mountpoint [-options]] location [...]
In most cases, it can be simplified to:
key is the path component used by
automountd(8) to find the
right map entry to use. It is also used to form the final mountpoint. A
wildcard (‘
*
’) can be used for the key. It
matches every directory that does not match other keys. Those directories will
not be visible to the user until accessed.
The
options field, if present, must begin with
-. When mounting the file system, options supplied to
auto_master and options specified in the map entry are
concatenated together. The special option
fstype is used to
specify file system type. It is not passed to the mount program as an option.
Instead, it is passed as an argument to
mount -t. The
default
fstype is ‘
nfs
’.
The special option
nobrowse is used to disable creation of
top-level directories for special and executable maps.
The optional
mountpoint field is used to specify multiple
mount points for a single key.
The
location field specifies the file system to be
mounted. Ampersands (‘
&
’) in the
location field are replaced with the value of
key. This is typically used with wildcards, like:
The
location field may contain references to variables,
like:
sys 192.168.1.1:/sys/${OSNAME}
Defined variables are:
ARCH
- Expands to the output of
uname
-p
.
CPU
- Same as
ARCH
.
HOST
- Expands to the output of
uname
-n
.
OSNAME
- Expands to the output of
uname
-s
.
OSREL
- Expands to the output of
uname
-r
.
OSVERS
- Expands to the output of
uname
-v
.
Additional variables can be defined with the
-D option of
automount(8) and
automountd(8).
To pass a location that begins with
/, prefix it with a colon.
For example,
:/dev/cd0
.
This example, when put into
/etc/auto_example, and with
auto_master referring to the map as described above,
specifies that the NFS share
192.168.1.1:/share/example/x
will be mounted on
/example/x/ when any process attempts to access that
mountpoint, with
intr and
nfsv4 mount
options, described in
mount_nfs(8):
x -intr,nfsv4 192.168.1.1:/share/example/x
Automatically mount an SMB share on access, as a guest user, without prompting
for a password:
share -fstype=smbfs,-N ://@server/share
Automatically mount the CD drive on access:
cd -fstype=cd9660 :/dev/cd0
SPECIAL MAPS
Special maps have names beginning with
-
. Supported
special maps are:
- -hosts
- Query the remote NFS server and map exported shares. This
map is traditionally mounted on /net. Access to files on
a remote NFS server is provided through the
/net/nfs-server-ip/share-name/
directory without any additional configuration. Directories for individual
NFS servers are not present until the first access, when they are
automatically created.
- -media
- Query devices that are not yet mounted, but contain valid
file systems. Generally used to access files on removable media.
- -noauto
- Mount file systems configured in
fstab(5) as
"noauto". This needs to be set up as a direct map.
- -null
- Prevent
automountd(8) from
mounting anything on the mountpoint.
It is possible to add custom special maps by adding them, as executable maps
named
special_foo, to the
/etc/autofs/
directory.
EXECUTABLE MAPS
If the map file specified in
auto_master has the execute bit
set,
automountd(8) will
execute it and parse the standard output instead of parsing the file contents.
When called without command line arguments, the executable is expected to
output a list of available map keys separated by newline characters.
Otherwise, the executable will be called with a key name as a command line
argument. Output from the executable is expected to be the entry for that key,
not including the key itself.
INDIRECT VERSUS DIRECT MAPS
Indirect maps are referred to in
auto_master by entries with a
fully qualified path as a mount point, and must contain only relative paths as
keys. Direct maps are referred to in
auto_master by entries
with
/-
as the mountpoint, and must contain only fully
qualified paths as keys. For indirect maps, the final mount point is
determined by concatenating the
auto_master mountpoint with
the map entry key and optional map entry mountpoint. For direct maps, the
final mount point is determined by concatenating the map entry key with the
optional map entry mountpoint.
The example above could be rewritten using direct map, by placing this in
auto_master:
and this in the
/etc/auto_example map file:
/example/x -intr,nfsv4 192.168.1.1:/share/example/x
/example/share -fstype=smbfs,-N ://@server/share
/example/cd -fstype=cd9660 :/dev/cd0
DIRECTORY SERVICES
Both
auto_master and maps may contain entries consisting of a
plus sign and map name:
Those entries cause
automountd(8) daemon to
retrieve the named map from directory services (like LDAP) and include it
where the entry was.
If the file containing the map referenced in
auto_master is
not found, the map will be retrieved from directory services instead.
To retrieve entries from directory services,
automountd(8) daemon runs
/etc/autofs/include, which is usually a shell script, with
map name as the only command line parameter. The script should output entries
formatted according to
auto_master or automounter map syntax
to standard output. An example script to use LDAP is included in
/etc/autofs/include_ldap. It can be symlinked to
/etc/autofs/include.
FILES
- /etc/auto_master
- The default location of the auto_master
file.
- /etc/autofs/
- Directory containing shell scripts to implement special
maps and directory services.
SEE ALSO
autofs(5),
automount(8),
automountd(8),
autounmountd(8)
AUTHORS
The
auto_master configuration file functionality was developed
by
Edward Tomasz Napierala
<
trasz@FreeBSD.org>
under sponsorship from the
FreeBSD Foundation.
The
auto_master configuration file functionality was ported to
DragonFly and
NetBSD by
Tomohiro Kusumi
<
kusumi.tomohiro@gmail.com>.
BUGS
The
-media
special map is currently unsupported on
NetBSD.