AUTOMOUNT(8) Maintenance Commands and Procedures AUTOMOUNT(8)

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(8)
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(8) 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(8), 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(5).

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), autofs(5), attributes(7),
nfssec(7), smf(7), automountd(8), mount(8), mount_nfs(8), svcadm(8)

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(8) 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(7), 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(8). The service's
status can be queried using the svcs(1) command.

illumos February 25, 2017 illumos