automount(1M) automount(1M)
NAME [Toc] [Back]
automount - install automatic mount points
SYNOPSIS [Toc] [Back]
/usr/sbin/automount [-f master-file] [-t duration] [-v]
DESCRIPTION [Toc] [Back]
The automount command installs autofs mount points and associates an
automount map with each mount point. The autofs filesystem monitors
attempts to access directories within it and notifies the automountd
daemon (see automountd(1M)). The daemon uses the map to locate a
filesystem, which it then mounts at the point of reference within the
autofs filesystem. You can assign a map to an autofs mount using an
entry in the /etc/auto_master map or a direct map.
If the filesystem 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 the following entry:
# Master map for automounter
#
/net -hosts -nosuid,soft,nobrowse
The first field in the master file specifies a directory on which an
autofs mount will be made, and the second field specifies the
automounter map to be associated with it. Mount options may be
supplied as an optional third field in the 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 a direct map, or to perform unmounts for entries
that have been removed.
The automounter maps, including the auto_master map, may be
distributed by NIS or NIS+. The Name Service Switch configuration
file, /etc/nsswitch.conf, determines where the automount command will
look for the maps.
Options [Toc] [Back]
-f master-file Specify a local master file for initialization.
When the -f option is used and the master file
specified is not found, then automount defaults to
/etc/auto_master and then to the NIS auto_master map.
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-t duration Specify a duration, in seconds, that a file system is
to remain mounted when not in use. The default is 600
(10 minutes).
-v Verbose mode. Notify of autofs mounts, unmounts or
other non-essential information. Messages are written
to standard error.
Map Entry Format [Toc] [Back]
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 as
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 pathname of the directory to mount.
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.
Replicated Filesystems [Toc] [Back]
Multiple location fields can be specified for replicated NFS
filesystems, in which case the information is used to try to increase
availability. The server chosen for the mount is the one with the
strongest preference based on a sorting order. Note that autofs does
not monitor the status of mounts when dealing with replicated
filesystems and does not select alternate servers.
The sorting order used gives strongest preference to servers on the
same local subnet with servers on the local net given the second
strongest preference. Among servers equally far away, response times
will determine the order if no weighting factors are used (see below).
If the list of locations contains some servers using the NFS Version 2
Protocol and some servers using the NFS Version 3 Protocol, then
automount will choose a subset of the list having only servers with
the same protocol. This subset is formed of servers using the NFS
Version 3 Protocol unless there are no such servers on the list or
there is a server using the NFS Version 2 Protocol that has the
strongest preference as described previously.
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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 default to 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/share/man
hosts alpha and bravo have the highest priority; host delta has the
lowest priority.
NOTE:
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.
In cases where each server has a different export point, you can still
apply the weighting. 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 [Toc] [Back]
The ampersand (&) character is expanded to the value of the key field
for the entry in which it occurs. In this case:
amy rowboatserver:/home/&
the & expands to amy.
Wildcard Key [Toc] [Back]
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/&
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it would allow automatic mounts in /config of any remote file system
whose location could be specified as:
hostname:/export/config/hostname
Variable Substitution [Toc] [Back]
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:
CPU The processor type. For example, IA64.
HOST The output of uname -n. The host name. For example,
rowboat.
OSNAME The output of uname -s. The OS name. For example, HP-UX.
OSREL The output of uname -r. The OS release name. For example,
B.11.00.
OSVERS The output of uname -v. The OS version. For example, C.
If a reference needs to be protected from neighboring characters, you
can surround the variable name with braces ({}).
Multiple Mounts [Toc] [Back]
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
automount would 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.
The autofs mount points must not be hierarchically related. automount
does not allow an autofs mount point to be created within another
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autofs mount.
Other Filesystem Types [Toc] [Back]
The automounter assumes NFS mounts as a default filesystem type.
Other filesystem types can be described using the -fstype mount
option. Other mount options specific to this filesystem type can be
combined with the -fstype option. The location field must contain
information specific to the filesystem type. If the location field
begins with a slash, a colon character must be prepended, for
instance, to mount a CD filesystem:
cdrom -fstype=hsfs,ro :/dev/sr0
or to perform an autofs mount:
src -fstype=autofs auto_src
Mounts using CacheFS are most useful when applied to an entire map as
map defaults (see cfsadmin(1M)). The following entry in the master
map describes cached home directory mounts. It assumes the default
location of the cache directory, /cache.
/home auto_home -fstype=cachefs,backfstype=nfs
Indirect Maps [Toc] [Back]
An indirect map allows you to specify mappings for the subdirectories
you wish to mount under the directory indicated in the
/etc/auto_master map or on the command line. In an indirect map, each
key consists of a simple name that refers to the subdirectory of one
or more filesystems that are to be mounted as needed.
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.
Direct Maps [Toc] [Back]
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.
Since each direct map entry results in a new autofs mount, such maps
should be kept short.
If a directory contains direct map mount points, then an ls -l in the
directory will force all the direct map mounts to occur.
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.
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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.
Included Maps [Toc] [Back]
The contents of another map can be included within a map with an entry
of the form:
+mapname
If mapname begins with a slash then 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: nis files
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 [Toc] [Back]
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 filesystems.
References to a directory under /net/hermes will refer to the
corresponding directory relative to hermes root.
The -null map, when indicated on the command line, cancels a previous
map for the directory indicated. This is most useful in the
/etc/auto_master map 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 [Toc] [Back]
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 standard output or no
output if the entry cannot be determined. A direct map cannot be made
executable.
Configuration and the auto_master Map [Toc] [Back]
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
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is located initially as a local file, /etc/auto_master.
Browsing [Toc] [Back]
Browsing of indirect maps allows all of the potential mount points to
be visible for that map regardless of whether they are mounted or not.
The -nobrowse option can be added to any indirect autofs map to
disable browsing. For example:
/net -hosts -nosuid,soft,nobrowse
In this case, any host names would only be visible in /net after they
are mounted. The -browse option enables browsing of autofs file
systems. This is the default for all indirect maps, although it is
suggested that the -hosts entry contain the -nobrowse option.
Note that, although a listing of the autofs directory associated with
an indirect map shows all potential mountable entries, the attributes
associated with those entries are temporary until the real filesystem
attributes can shown once the filesystem has been mounted.
Network Information Service (NIS) and Yellow Pages (YP) [Toc] [Back]
The Network Information Service (NIS) was formerly known as Sun Yellow
Pages (YP). The functionality of the two remains the same.
RETURN VALUE [Toc] [Back]
automount returns:
0 Success
1 Failure
3 Map not found
AUTHOR [Toc] [Back]
automount was developed by Sun Microsystems, Inc.
FILES [Toc] [Back]
/etc/auto_master Master automount map.
/etc/nsswitch.conf Name service switch configuration
file.
/usr/sbin/automount autofs automount command.
SEE ALSO [Toc] [Back]
automountd(1M), cfsadmin(1M), mount(1M).
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