automount - Automatically and transparently mounts and
unmounts NFS file systems
/usr/sbin/automount [-hmnpTv] [-D name=value] [-f masterfile]
[-M mount-directory] [-tl duration] [-tm interval]
[-tw interval] [directory map [-mount-options]]
Includes the host name in mount-point pathnames. The host
name is inserted just after the mount-directory in a
mount-point pathname. This ensures that NFS mount points
to different servers are placed in separate directories.
This avoids a limitation of getwd(3). Ignores directorymapname
pairs listed in the auto.master NIS database.
Disables dynamic mounts. Lookups intercepted by the automount
daemon succeed only when the target file system has
been previously mounted. Uses local mounts for primary
Internet addresses and NFS loopback mounts for Internet
alias addresses. Without this option, the command's
default behavior is to bypass NFS for all local Internet
addresses, including Internet alias addresses. Traces all
NFS requests received by the daemon. Information about
the details of the request are expanded and sent to standard
output. Logs status messages to the console.
(Stands for "verbose.") Defines an automount environment
variable by assigning value to the variable. Uses masterfile
for a list of initial directory to mapname pairs,
ahead of the auto.master NIS map. If an entry exists in
both master-file and auto.master, the one specified in
master-file is used since it is read first. Similarly,
entries on the command line take precedence over masterfile
entries. This technique can be used to replace
entries in global maps with your own. Uses mount-directory
instead of the default, /tmp_mnt. Specifies a duration
(in seconds) that a file system is to remain mounted
when not in use. The default is 5 minutes. Specifies an
interval (in seconds) between attempts to mount a file
system. The default is 30 seconds. Specifies an interval
(in seconds) between attempts to unmount file systems that
have exceeded their cached times. The default is 1 minute.
Specifies the full pathname of a local directory if the
map argument is the name of an indirect map or the name of
a special map. If the map argument is the name of a direct
map, the dummy directory "/-" is specified as the directory.
Names a map that the automount command uses to find
the mount points and locations. This can either be a file
name, an NIS map name, or a special map name. Specifies
the mount options to be applied to all of the directories
listed in map. If mount options are listed in the specified
map, they take precedence over these options.
The automount daemon automatically and transparently
mounts and unmounts NFS file systems on an as-needed
basis. It provides an alternative to using /etc/fstab for
NFS mounting file systems on client machines.
Note that the automount daemon will be retired in a future
release of the operating system. For information about
migrating from Automount to its replacement, AutoFS, see
Network Administration: Services. For more information
about AutoFS, see autofsd(8).
The automount daemon can be started from the /etc/rc.config.common
file or from the command line. Once started,
it sleeps until a user attempts to access a directory that
is associated with an automount map, or any directory or
file in the directory structure. The daemon awakes and
consults the appropriate map and mounts the NFS file system.
By default, the daemon mounts the remote file system
under the directory /tmp_mnt and creates a symbolic link
to the temporary mount point. If the indicated directory
has not already been created, the daemon creates it and
removes it after automatic unmount. After a specified
period of inactivity on a file system, 5 minutes by
default, the automount daemon unmounts that file system.
The maps indicate where to find the file system to be
mounted and the mount options to use. The names of the
maps are passed to automount from the command line or from
a master map. If the command line and the master map contain
contradictory arguments, the command line arguments
take precedence.
Note
The automount program reads the master map only at
startup. If you make any changes to the master map, you
must restart automount.
An individual automount map is either local or served by
NIS. A system, however, can use both local and NIS automount
maps. When a map is referenced, the automount daemon
checks whether a full pathname is specified. If it
is, automount looks for the designated mapname locally.
If the mapname is not a full pathname, automount looks for
an NIS map by that name.
By default, automount uses UDP. If the tcp option is
specified in a map, automount will try TCP. If TCP is not
available, automount will then use UDP.
Maps [Toc] [Back]
Conventionally, automount maps are files that are located
in the /etc directory with names that have the prefix
auto. They indicate which remote file systems to mount,
where to mount them, and which options to use.
The Master Map [Toc] [Back]
The automount program can consult a master map, which contains
entries that point to other maps that can be either
direct or indirect. If NIS is running, automount checks
for the presence of an NIS map named auto.master; you are
not required to run NIS or have an auto.master map. A master
map can also be a file whose location is specified
with the -f command line option.
The master map provides automount with a list of maps, and
with arguments that pertain to each of the maps. Each line
in the master map has the following syntax: directory
map [mount-options]
Specifies the full pathname of a local directory if the
map argument is the name of an indirect map or the name of
a special map. If the map argument is the name of a direct
map, the dummy directory "/-" is specified as the directory.
Names the map that the automount command uses to
find the mount points and locations. This can either be a
file name, an NIS map name, or a special map name. Lists
the options used to regulate the mounting of entries
listed in map.
Direct Maps [Toc] [Back]
Direct maps specify which remote file systems to mount
locally and what the local mount points are. They also can
specify mount options. Direct maps have the following syntax:
key [mount-options] location
Specifies the full pathname of the mount point. Lists the
options for this specific mount. When present, these
options override any mount options specified on the command
line or in the master map. Specifies the location of
the resource being mounted and uses the format
server:pathname. Multiple location fields can be specified;
see Replicated File Systems for more information.
Indirect Maps [Toc] [Back]
Indirect maps have the same format as direct maps. However,
unlike the key in a direct map, the key in an indirect
map is a simple name that does not begin with a
slash. (Remember that the indirect map as a whole has been
associated with a directory specified in the master map or
on the command line. The entries in an indirect map list
subdirectories that are individually mounted within the
directory associated with the map.)
Special Maps [Toc] [Back]
The -hosts map is a special automount map that is used to
access all directories exported by a server to a client.
The following command allows a client to access directories
that are exported from any host in its /etc/hosts
file, the NIS hosts database: # automount /net -hosts
For example, suppose that hera and sheba are both hosts on
a local area network that is running NIS. If superuser on
hera enters the automount /net -hosts command, users on
hera can access any directories that sheba exports to
hera. All of the exported directories are mounted under
/net/sheba on hera.
The -null map, when indicated on the command line, cancels
the map associated with the directory indicated. It can
be used to cancel a map specified in the master map. For
example, invoking the automount command in the following
manner causes the /net entry in auto.master to be ignored:
# automount /net -null
Pattern Matching [Toc] [Back]
The ampersand (&) is expanded into the key field in a map
wherever it appears. In the following example, the ampersand
(&) expands to oak:
#key mount_options location # oak
&:/export/&
The asterisk (*), when supplied as the key field, is recognized
as the catch-all entry. It is used to substitute
for lines that are all formatted similarly. Any entry following
the asterisk is ignored. In the following example,
the automount program uses the asterisk to match any host
name other than oak:
#key mount_options location # oak
&:/export/& * &:/home/&
Environment Variables [Toc] [Back]
The value of an environment variable can be used within an
automount map by prefixing a dollar sign ($) to its name.
You can also use braces to delimit the name of the variable
from appended letters or digits. The environment
variables can be inherited from the environment or can be
explicitly defined with the -D command line option.
Multiple Mounts [Toc] [Back]
A multiple mount entry causes several NFS mount points to
be mounted and unmounted together. Multiple mounts have
the following syntax: key mountpoint [mount-options] location...\
[mountpoint [mount-options] location...] ...
Specifies the full pathname or simple name of the mount
point, depending on whether it is a direct or indirect map
entry. Specifies the full pathname of a local directory.
All mount points must begin with a slash (/). A slash is
acceptable as the first mountpoint. Lists the options for
this specific mount. When present, these options override
any mount options specified on the command line or in the
master map. Specifies the location of the resource being
mounted and uses the format server:pathname. Multiple
location fields can be specified; see Replicated File Systems
for more information.
If multiple mounts are hierarchically related, the order
in which they appear in the entry is the order in which
they are mounted.
In the following example, the directories /usr/local,
/usr/local/bin, /usr/local/src, and /usr/local/tools are
mounted from the machines host1, host2, host3, and host4,
respectively. When the root of the hierarchy is referenced,
the automount program mounts the whole hierarchy.
/usr/local \
/ -ro host1:/usr/local \
/bin -ro host2:/usr/local/bin \
/src -ro host3:/usr/local/src \
/tools -ro host4:/usr/src/tools
Readability has been improved by splitting the entry into
five lines and indenting the continuation lines.
Shared Mounts [Toc] [Back]
A shared mount prevents duplicate mounts of a remote file
system by creating symbolic links for subdirectories that
the file system contains. When you mount multiple directories
from within a common remote directory, you can
specify the location field as follows: host:path:subdir
Specifies the remote host from which to mount the file
system. Specifies a pathname for the common directory
that contains the directories you want to mount. Specifies
the name of a subdirectory to which you want to make
a symbolic link.
Suppose an indirect map called /auto.myindirect is specified
in a master file as follows:
/mydir /auto.myindirect
And the /auto.myindirect map consists of the following
entries:
mybin host1:/usr/staff/diane:bin mystuff
host1:/usr/staff/diane:stuff
When a user accesses a file in /mydir/mybin, the automount
daemon mounts host1:/usr/staff/diane, but creates a symbolic
link called /mydir/mybin to the bin subdirectory in
the temporarily mounted file system. If a user immediately
tries to access a file in /mydir/mystuff, the automount
daemon needs only to create a symbolic link that points to
the stuff subdirectory because the /usr/staff/diane directory
is already mounted. With the following map, the daemon
would perform two separate mount operations:
mybin host1:/usr/staff/diane/bin mystuff
host1:/usr/staff/diane/stuff
Replicated File Systems [Toc] [Back]
You can specify multiple locations for a single mount. If
a file system is located on several servers and one of the
servers is disabled, the file system can be mounted from
one of the other servers. This makes sense only when
mounting a read-only file system.
In the following example, the reference pages can be
mounted from host1, machine2, or system3:
/usr/man\
-ro,soft host1:/usr/man \
machine2:/usr/man \
system3:/usr/man
The preceding example can also be expressed as a list of
servers, separated by commas and followed by a colon and
the pathname, for example:
/usr/man -ro,soft host1,machine2,system3:/usr/man
This syntax is valid only if the pathname is the same on
each server.
When you access the reference pages, the automount daemon
issues a ping (NFS v2 noop request) to each of the specified
servers concurrently. The server that first responds
to the ping request is used for the mount.
Sending the SIGTERM signal (kill -TERM) to the automount
daemon causes it to unmount all file systems that it has
mounted, and to exit. This is the preferred method. If
you send any other signals that automount cannot catch
(for example, kill -KILL or kill -INT), any NFS mount
points that automount was not able to remove before exiting
will hang. The hang will occur from any program that
attempts to access those mount points. You must reboot
the system in order to remove the NFS mount points.
Sending the SIGHUP signal to the automount daemon causes
it to reread the system mount table to update its internal
record of currently mounted file systems. If a file system
mounted with automount is unmounted by a umount command,
automount should be forced to reread the system
mount table.
Shell filename expansion does not apply to objects not
currently mounted.
Because automount is singlethreaded, any request that is
delayed by a slow or nonresponding NFS server will delay
all subsequent automount requests until the delayed
request has been completed.
The following is a sample auto.master map:
# # mount-point mapname mountoptions
# /net -hosts /home
auto.indirect -rw /-
auto.direct -ro,intr The following is a typical
automount indirect map:
# # key mount-options location
# john
merge:/usr/staff/john mary
stripe:/usr/staff/mary fred
blur:/usr/staff/fred The following is a typical
automount direct map:
# # key mount-options location
# /usr/source -ro
merge:/usr/src/proto /usr/local
blur:/usr/bin/tools The following is a sample indirect
map that specifies multiple mount locations
for the file system reference. The file system is
mounted from the first server to respond to the
mount request.
reference -ro
earl:/usr/src/ref\
fern:/usr/staff/ron/ref\
irv:/usr/backup/reference
Directory where automounted file systems reside.
Commands: autofsd(8), autofsmount(8), mount(8)
Network Administration: Services
automount(8)
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