AUTOMOUNT(1M-SysV) RISC/os Reference Manual AUTOMOUNT(1M-SysV)
NAME
automount - automatically mount NFS file systems
SYNOPSIS
automount [ -mnTv ] [ -D name=value ] [ -f master-file ]
[ -M mount-directory ] [ -R root ] [ -S ] [ -t sub-
options ]
[ directory mapname [ -mount-options ] ] ...
DESCRIPTION
automount is a daemon that will automatically and tran-
sparently mount an NFS file system whenever a file or direc-
tory within in that system is opened. automount forks a
daemon, which appears to be an NFS server to the kernel;
lookups on the specified directory are intercepted by this
daemon, which uses the map contained in mapname to determine
a server, exported file system, and appropriate mount
options for a given file system. The named map can either
be a file on the local system, or a Network Information Ser-
vice map. directory is a full pathname starting with a `/'.
When supplied, -mount-options consists of the leading - and
a comma-separated list of mount(1M) options; if mount
options are specified in the map, however, those in the map
take precedence.
Once mounted, members of the directory are made available
using a symbolic link to the real mount point within a tem-
porary directory.
If directory does not exist, the daemon creates it, and then
removes it automatically when the daemon exits.
Since the name-to-location binding is dynamic, updates to a
Network Information Service map are transparent to the user.
This obviates the need to ``pre-mount'' shared file systems
for applications that have ``hard coded'' references to
files. It also obviates the need to maintain records of
which hosts must be mounted for what applications.
Maps
automount looks first for the indicated mapname in a file by
that name. If there is no such file, it looks for a NIS map
by that name.
An automount map is composed of a list of mappings, with one
mapping per line. Each mapping is composed of the following
fields:
basename [-mount-options] location [...]
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where basename is the name of a subdirectory within the
directory specified in the automount command line (not a
relative pathname). The location field consists of an entry
of the form:
host:directory[:subdir]
where host is the name of the host from which to mount the
file system, directory is the pathname of the directory to
mount, and subdir, when supplied, is the name of a subdirec-
tory to which the symbolic link is made. This can be used
to prevent duplicate mounts in cases where multiple direc-
tories in the same remote file system are accessed.
The contents of a NIS map can be included within a map by
adding an entry of the form:
+mapname
A mapping can be continued across line breaks using a \ as
the last character before the NEWLINE. Comments begin with a
# and end at the subsequent NEWLINE.
If more than one location is supplied, there is no guarantee
as to which location will be used; the first location to
respond to the mount request gets mounted. The mount-
options field can be used to supply options to the mount(1M)
command for the mounted file system.
Special Maps
There are two special maps currently available. The -hosts
map uses the Network Information Service hosts.byname map to
locate a remote host when the hostname is specified as a
subdirectory of directory. This map specifies mounts of all
exported file systems from any host. For instance, if the
following automount command is already in effect:
automount /net -hosts
then a reference to /net/hermes/usr would initiate an
automatic mount of all file systems from hermes that auto-
mount can mount; references to a directory under /net/hermes
will refer to the corresponding directory on hermes. The
-passwd map uses the passwd(4) database to attempt to locate
the home directory of a user. For instance, if the follow-
ing automount command is already in effect:
automount /homes -passwd
then if the home directory shown in the passwd entry for the
user username has the form /dir/server/username, and server
matches the host system on which that directory resides,
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references to files in /homes/username result in the file
system containing that directory being mounted if necessary,
and all such references will refer to that user's home
directory.
Configuration
automount normally consults the auto.master Network Informa-
tion Service configuration database for a list of initial
directory to mapname pairs, and sets up automatic mounts for
them in addition to those given on the command line; if
there are duplications, the command-line arguments take pre-
cedence. (Note that this database contains arguments to the
automount command, rather than mappings, and that automount
does not look for an auto.master file on the local host.)
At system boot, the automounter gets started if the sentinel
file /etc/automount.conf is present. The first line of this
file should contain any parameters which are to be passed at
boottime. /etc/automount.conf.sample contains an example.
Killing the Automounter
In order to kill automount, type:
kill <automount pid>
Before exiting, automount attempts to unmount all non-busy
filesystems, subject to the constraint that all of a
machine's filesystems are non-busy before any of that
machine's filesystems are unmounted. Do not use umount(1M)
to unmount any NFS filesystems if you plan on starting
another automount process soon. Inconsistencies will result
when all of a specific machine's filesystems can not be
unmounted at the same time.
OPTIONS
-m Suppress initialization of directory-mapname pairs
listed in the auto.master Network Information Service
database.
-n Disable dynamic mounts. With this option, references
through the automount daemon only succeed when the tar-
get filesystem has been previously mounted. This can
be used to prevent NFS servers from cross-mounting each
other.
-T Trace. Expand each NFS call and display it on the
standard output.
-v Enable verbose error messages.
-D name=value
Set environment variables. See automount document in
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the system administrator's guide for examples.
-f master-file
Specify the master map. See automount document in the
system administrator's guid for examples.
-M mount-directory
Rename the temporary directory used by the automounter.
The default is /tmp_dir
-R root
This option is recommended when a machine may have many
NFS filesystems mounted at once. Instead of mounting a
host's filesystems on
/tmp_dir/access_point/hostname/..., automount mounts
them on /tmp_dir/access_point/hostname/<root>/...,
-S Instead of mounting a host's filesystems on
/tmp_dir/access_point/hostname/..., automount mounts
them on /tmp_dir/hostname/...
-tl duration
Specify a duration, in seconds, that a looked up name
remains cached when not in use. The default is 60
minutes. NOTE: This was changed from 5 minutes because
it would do more damage to attempt this too often.
-tm interval
Specify an interval, in seconds, between attempts to
mount a filesystem. The default is 30 seconds.
-tw interval
Specify an interval, in seconds, between attempts to
dismount filesystems that have exceeded their cached
times. The default is 60 minutes. NOTE: This was
changed from 1 minute because it would do more damage
to attempt this too often.
EXAMPLES
file example
Mount the root file system of the machine oddjob to
/n/oddjob. The map file is /etc/map and contains
oddjob oddjob:/
Access as follows:
tutorial# automount /n /etc/map
tutorial# cd /n/oddjob
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NOTE: This example is inadequate for most purposes and is
placed here just to clarify syntax. Please read the auto-
mounter document in the System Administrator's Guide for
more complete examples.
Host-to-host example
tutorial# automount -M /NET -R root -S /n -hosts
-rw,bg,soft,intr,timeo=3,retry=3
Access by:
tutorial# cd /n/jaws
This setup will mount all mountable NFS file systems from
jaws onto /NET/jaws/root/... . /n/jaws becomes a shorthand
to access /NET/jaws/root.
NIS example
tutorial# automount -m /net -hosts
Provide automount access to the exported file systems of any
host in the Network Information Service hosts.byname data-
base, by prefixing the pathname with /net/hostname/ :
tutorial% ls /net/hermes/usr/src ...
FILES
/tmp_mnt directory under which filesystems are
dynamically mounted
/etc/automount.conf Configuration file which causes auto-
mount to start at boottime
/etc/automount.conf.sample
A sample configuration file
SEE ALSO
mount(1M).
System Administrator's Guide.
BUGS
Shell filename expansion does not apply to objects not
currently mounted or cached. For instance, in the above
example, the command ls /net/* might not list hermes as a
subdirectory of /net.
ORIGIN
Sun Microsystems, NFS 4.0
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