AUTOMOUNT(1M) Maintenance Commands AUTOMOUNT(1M)

NAME


automount - install automatic mount points

SYNOPSIS


automount [-v] [-t duration]

DESCRIPTION


The automount utility installs autofs mount points and associates an
automount map with each mount point. It starts the automountd(1M) daemon
if it finds any non-trivial entries in either local or distributed
automount maps and if the daemon is not already running. The autofs file
system monitors attempts to access directories within it and notifies the
automountd(1M) daemon. The daemon uses the map to locate a file system,
which it then mounts at the point of reference within the autofs file
system. A map can be assigned to an autofs mount using an entry in the
/etc/auto_master map or a direct map.

If the file system is not accessed within an appropriate interval (10
minutes by default), the automountd daemon unmounts the file system.

The file /etc/auto_master determines the locations of all autofs mount
points. By default, this file contains three entries:

# Master map for automounter
#
+auto_master
/net -hosts -nosuid
/home auto_home

The +auto_master entry is a reference to an external NIS master map. If
one exists, then its entries are read as if they occurred in place of the
+auto_master entry. The remaining entries in the master file specify a
directory on which an autofs mount will be made followed by the automounter
map to be associated with it. Optional mount options may be supplied as an
optional third field in the each entry. These options are used for any
entries in the map that do not specify mount options explicitly. The
automount command is usually run without arguments. It compares the
entries /etc/auto_master with the current list of autofs mounts in
/etc/mnttab and adds, removes or updates autofs mounts to bring the
/etc/mnttab up to date with the /etc/auto_master. At boot time it installs
all autofs mounts from the master map. Subsequently, it may be run to
install autofs mounts for new entries in the master map or the direct map,
or to perform unmounts for entries that have been removed from these maps.

Automount with Solaris Trusted Extensions


If a system is configured with Solaris Trusted Extensions, additional
processing is performed to facilitate multilevel home directory access. A
list of zones whose labels are dominated by the current zone is generated
and default auto_home automount maps are generated if they do not currently
exist. These automount maps are named auto_home_zonename, where zonename
is the name of each zone's lower-level zone. An autofs mount of each such
auto_home map is then performed, regardless of whether it is explicitly or
implicitly listed in the master map. Instead of autofs mounting the
standard auto_home map, the zone uses an auto_home file appended with its
own zone name. Each zone's auto_home map is uniquely named so that it can
be maintained and shared by all zones using a common name server.

By default, the home directories of lower-level zones are mounted read-only
under /zone/zonename/export/home when each zone is booted. The default
auto_home_zonename automount map specifies that path as the source
directory for an lofs remount onto /zone/zonename/home/username. For
example, the file auto_home_public, as generated from a higher level zone
would contain:

+auto_home_public
* -fstype=lofs :/zone/public/export/home/&

When a home directory is referenced and the name does not match any other
keys in the auto_home_public map, it will match this loopback mount
specification. If this loopback match occurs and the name corresponds to a
valid user whose home directory does not exist in the public zone, the
directory is automatically created on behalf of the user.

OPTIONS


The following options are supported:

-v Verbose mode. Notifies of autofs mounts, unmounts, or other non-
essential information.

-t duration
Specifies a duration, in seconds, that a file system is to remain
mounted when not in use. The default is 10 minutes.

USAGE


Map Entry Format


A simple map entry (mapping) takes the form:

key [-mount-options] location...

where key is the full pathname of the directory to mount when used in a
direct map, or the simple name of a subdirectory in an indirect map.
mount-options is a comma-separated list of mount options, and location
specifies a file system from which the directory may be mounted. In the
case of a simple NFS mount, the options that can be used are specified in
mount_nfs(1M), and location takes the form:

host:pathname

host is the name of the host from which to mount the file system, and
pathname is the absolute pathname of the directory to mount.

Options to other file systems are documented in the other mount_* reference
manual pages.

Replicated File Systems


Multiple location fields can be specified for replicated NFS file systems,
in which case automount and the kernel will each try to use that
information to increase availability. If the read-only flag is set in the
map entry, automountd mounts a list of locations that the kernel may use,
sorted by several criteria. Only locations available at mount time will be
mounted, and thus be available to the kernel. When a server does not
respond, the kernel will switch to an alternate server. The sort ordering
of automount is used to determine how the next server is chosen. If the
read-only flag is not set, automount will mount the best single location,
chosen by the same sort ordering, and new servers will only be chosen when
an unmount has been possible, and a remount is done. Servers on the same
local subnet are given the strongest preference, and servers on the local
net are given the second strongest preference. Among servers equally far
away, response times will determine the order if no weighting factors (see
below) are used.

If the list includes server locations using both the NFS Version 2 Protocol
and the NFS Version 3 Protocol, automount will choose only a subset of the
server locations on the list, so that all entries will be the same
protocol. It will choose servers with the NFS Version 3 Protocol so long
as an NFS Version 2 Protocol server on a local subnet will not be ignored.
See the FIXME for additional details.

If each location in the list shares the same pathname then a single
location may be used with a comma-separated list of hostnames:

hostname,hostname...:pathname

Requests for a server may be weighted, with the weighting factor appended
to the server name as an integer in parentheses. Servers without a
weighting are assumed to have a value of zero (most likely to be selected).
Progressively higher values decrease the chance of being selected. In the
example,

man -ro alpha,bravo,charlie(1),delta(4):/usr/man

hosts alpha and bravo have the highest priority; host delta has the lowest.

Server proximity takes priority in the selection process. In the example
above, if the server delta is on the same network segment as the client,
but the others are on different network segments, then delta will be
selected; the weighting value is ignored. The weighting has effect only
when selecting between servers with the same network proximity. The
automounter always selects the localhost over other servers on the same
network segment, regardless of weighting.

In cases where each server has a different export point, the weighting can
still be applied. For example:

man -ro alpha:/usr/man bravo,charlie(1):/usr/share/man \
delta(3):/export/man

A mapping can be continued across input lines by escaping the NEWLINE with
a backslash ("\"). Comments begin with a number sign ("#") and end at the
subsequent NEWLINE.

Map Key Substitution


The ampersand ("&") character is expanded to the value of the key field for
the entry in which it occurs. In this case:

jane sparcserver:/home/&

the & expands to jane.

Wildcard Key


The asterisk ("*") character, when supplied as the key field, is recognized
as the catch-all entry. Such an entry will match any key not previously
matched. For instance, if the following entry appeared in the indirect map
for /config:

* &:/export/config/&

this would allow automatic mounts in /config of any remote file system
whose location could be specified as:

hostname:/export/config/hostname

Note that the wildcard key does not work in conjunction with the -browse
option.

Variable Substitution


Client specific variables can be used within an automount map. For
instance, if $HOST appeared within a map, automount would expand it to its
current value for the client's host name. Supported variables are:

NAME OUTPUT OF DESCRIPTION (EXAMPLE)
ARCH arch architecture name ("sun4")
CPU uname -p processor type ("sparc")
HOST uname -n host name ("myhost")
KARCH arch -k or uname -m kernel architecture name or machine
hardware name ("sun4u")
OSNAME uname -s OS name ("SunOS")
OSREL name -r OS release name ("5.3")
OSVERS uname -v OS version ("beta1.0")
NATISA isainfo -n native instruction set architecture for
the system ("sparcv9")
PLATFORM uname -i platform name ("SUNW,Sun-Fire-V240")

If a reference needs to be protected from affixed characters, you can
surround the variable name with curly braces ("{}").

Multiple Mounts


A multiple mount entry takes the form:

key [-mount-options] [[mountpoint] [-mount-options] location...]...

The initial mountpoint is optional for the first mount and mandatory for
all subsequent mounts. The optional mountpoint is taken as a pathname
relative to the directory named by key. If mountpoint is omitted in the
first occurrence, a mountpoint of / (root) is implied.

Given an entry in the indirect map for /src:

beta -ro \
/ svr1,svr2:/export/src/beta \
/1.0 svr1,svr2:/export/src/beta/1.0 \
/1.0/man svr1,svr2:/export/src/beta/1.0/man

All offsets must exist on the server under beta. automount will
automatically mount /src/beta, /src/beta/1.0, and /src/beta/1.0/man, as
needed, from either svr1 or svr2, whichever host is nearest and responds
first.

Other File System Types


The automounter assumes NFS mounts as a default file system type. Other
file system types can be described using the fstype mount option. Other
mount options specific to this file system type can be combined with the
fstype option. The location field must contain information specific to the
file system type. If the location field begins with a slash, a colon
character must be prepended, for instance, to mount a CD file system:

cdrom -fstype=hsfs,ro :/dev/sr0

or to perform an autofs mount:

src -fstype=autofs auto_src

Use this procedure only if you are not using Volume Manager.

See the NOTES section for information on option inheritance.

Indirect Maps


An indirect map allows you to specify mappings for the subdirectories you
wish to mount under the directory indicated on the command line. In an
indirect map, each key consists of a simple name that refers to one or more
file systems that are to be mounted as needed.

Direct Maps


Entries in a direct map are associated directly with autofs mount points.
Each key is the full pathname of an autofs mount point. The direct map as
a whole is not associated with any single directory.

Direct maps are distinguished from indirect maps by the - key. For
example:

# Master map for automounter
#
+auto_master
/net -hosts -nosuid,nobrowse
/home auto_home -nobrowse
/- auto_direct

Included Maps


The contents of another map can be included within a map with an entry of
the form

+mapname

If mapname begins with a slash, it is assumed to be the pathname of a local
file. Otherwise, the location of the map is determined by the policy of
the name service switch according to the entry for the automounter in
/etc/nsswitch.conf, such as

automount: files nis

If the name service is files, then the name is assumed to be that of a
local file in /etc. If the key being searched for is not found in the
included map, the search continues with the next entry.

Special Maps


There are two special maps available: -hosts and -null. The -hosts map is
used with the /net directory and assumes that the map key is the hostname
of an NFS server. The automountd daemon dynamically constructs a map entry
from the server's list of exported file systems. References to a directory
under /net/hermes will refer to the corresponding directory relative to
hermes root.

The -null map cancels a previous map for the directory indicated. This is
most useful in the /etc/auto_master for cancelling entries that would
otherwise be inherited from the +auto_master include entry. To be
effective, the -null entries must be inserted before the included map
entry.

Executable Maps


Local maps that have the execute bit set in their file permissions will be
executed by the automounter and provided with a key to be looked up as an
argument. The executable map is expected to return the content of an
automounter map entry on its stdout or no output if the entry cannot be
determined. A direct map cannot be made executable.

Configuration and the auto_master Map
When initiated without arguments, automount consults the master map for a
list of autofs mount points and their maps. It mounts any autofs mounts
that are not already mounted, and unmounts autofs mounts that have been
removed from the master map or direct map.

The master map is assumed to be called auto_master and its location is
determined by the name service switch policy. Normally the master map is
located initially as a local file /etc/auto_master.

Browsing


The automountd daemon supports browsability of indirect maps. This allows
all of the potential mount points to be visible, whether or not they are
mounted. The -nobrowse option can be added to any indirect autofs map to
disable browsing. For example:

/net -hosts -nosuid,nobrowse
/home auto_home

In this case, any hostnames would only be visible in /net after they are
mounted, but all potential mount points would be visible under /home. The
-browse option enables browsability of autofs file systems. This is the
default for all indirect maps.

The -browse option does not work in conjunction with the wildcard key.

Restricting Mount Maps


Options specified for a map are used as the default options for all the
entries in that map. They are ignored when map entries specify their own
mount options.

In some cases, however, it is desirable to force nosuid, nodevices,
nosetuid, or noexec for a complete mount map and its submounts. This can
be done by specifying the additional mount option, -restrict.

/home auto_home -restrict,nosuid,hard

The -restrict option forces the inheritance of all the restrictive options
nosuid, nodevices, nosetuid, and noexec as well as the restrict option
itself. In this particular example, the nosuid and restrict option are
inherited but the hard option is not. The restrict option also prevents
the execution of "executable maps" and is enforced for auto mounts
established by programs with fewer than all privileges available in their
zone.

FILES


/etc/auto_master
Master automount map.

/etc/auto_home
Map to support automounted home directories.

/etc/nsswitch.conf
Name service switch configuration file. See nsswitch.conf(4).

EXIT STATUS


The automount utility exits 0 on success, and >0 if an error occurs.

SEE ALSO


isainfo(1), ls(1), svcs(1), uname(1), automountd(1M), mount(1M),
mount_nfs(1M), svcadm(1M), autofs(4), attributes(5), nfssec(5), smf(5)

NOTES


autofs mount points must not be hierarchically related. automount does not
allow an autofs mount point to be created within another autofs mount.

Since each direct map entry results in a new autofs mount such maps should
be kept short.

Entries in both direct and indirect maps can be modified at any time. The
new information is used when automountd next uses the map entry to do a
mount.

New entries added to a master map or direct map will not be useful until
the automount command is run to install them as new autofs mount points.
New entries added to an indirect map may be used immediately.

As of the Solaris 2.6 release, a listing (see ls(1)) of the autofs
directory associated with an indirect map shows all potential mountable
entries. The attributes associated with the potential mountable entries
are temporary. The real file system attributes will only be shown once the
file system has been mounted.

Default mount options can be assigned to an entire map when specified as an
optional third field in the master map. These options apply only to map
entries that have no mount options. Note that map entities with options
override the default options, as at this time, the options do not
concatenate. The concatenation feature is planned for a future release.

When operating on a map that invokes an NFS mount, the default number of
retries for the automounter is 0, that is, a single mount attempt, with no
retries. Note that this is significantly different from the default
(10000) for the mount_nfs(1M) utility.

The Network Information Service (NIS) was formerly known as Sun Yellow
Pages (YP). The functionality of the two remains the same.

The automount service is managed by the service management facility,
smf(5), under the service identifier:

svc:/system/filesystem/autofs:default

Administrative actions on this service, such as enabling, disabling, or
requesting restart, can be performed using svcadm(1M). The service's
status can be queried using the svcs(1) command.

illumos February 25, 2017 illumos