Query: automount
OS: ultrix
Section: 8nfs
Format: Original Unix Latex Style Formatted with HTML and a Horizontal Scroll Bar
automount(8nfs) automount(8nfs) Name automount - automatically and transparently mounts and unmounts NFS file systems Syntax /usr/etc/automount [ -mnTv ] [ -D name= value ] [ -f master-file ] [ -M mount-directory ] [ -tl duration ] [ -tm interval ] [ -tw interval ] [ directory mapname [ - mount-options ]] Description The command transparently mounts and unmounts NFS file systems on an as-needed basis. It is useful for mounting file systems and directo- ries that are needed only occasionally, and it provides an alternative to using for NFS mounting file systems on client machines. The program can be started from the file or the command line. The daemon forked by the program sleeps until a user attempts to access a directory that is associated with an map. The daemon then consults the appropriate map and mounts the NFS file system. If the indicated directory has not already been created, the daemon creates it and removes it after automatic Local maps are typically located in the directory but can be placed in any directory. You also can use the Yellow Pages Service to dis- tribute maps. The maps indicate where to find the file system to be mounted, the local mount point, and mount options. After a specified period of inactivity on a file system, 5 minutes by default, the daemon unmounts that file system. An individual automount map is either local or served by the Yellow Pages. A system, however, can use both local and Yellow Pages auto- mount maps. When a map is referenced, the program first looks for the designated mapname locally. If it cannot find the mapname locally, it looks for a Yellow Pages map by that name. The names of the maps are passed to from the command line, or from a master map. If the command line and the master map contain contradictory arguments, those on the command line take precedence. By default, the daemon mounts the remote file system under the directory and creates a symbolic link between the requested and the actual mount points. Maps Conventionally, maps are files that are located in the directory with names that have the prefix They indicate which remote file systems to mount, where to mount them, and which options to use. The Master Map The program can consult a master map, which contains entries that point to other maps that can be either direct or indirect. If Yellow Pages is running, checks for the presence of a YP map named You are not required to run YP or have an map. A master map can also be a file whose location is specified with the command line option. The master map provides with a list of maps, and with arguments that pertain to each of the maps. Each line in the master map has the fol- lowing syntax: mount-point map [mount-options] o Mount-point is 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 mount-point. o Map is the name of the map the automount command uses to find the mount points and locations. This can either be a filename, a YP map name, or a special map name. o Mount-options is a list of options used to regulate the mounting of entries listed in map. Direct Maps Direct maps specify which remote file systems to mount locally and what the local mount points are. They do not point to other maps. They also can specify mount options. Direct maps have the following syntax: key [mount-options] location o Key is the full pathname of the mount point. o Mount-options are the options for this specific mount. When present, these options override any mount options specified on the command line or in the master map. o Location is the location of the resource being mounted, specified as: server:pathname. Multiple location fields can be specified, in which case sends multiple mount requests and mounts from the first server to respond. Indirect Maps Indirect maps have the same format as direct maps. The only difference between a direct and an indirect map is that the key in a direct map is a full pathname, whereas 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 The map is a special 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 file, the Yellow Pages hosts database, or the BIND database. # automount /net -hosts For example, suppose that and are both hosts on a local area network that is running Yellow Pages. If the file on contains the command then users on can access any directories that exports to All of the exported directories are mounted under on The map, when indicated on the command line, cancels the map associated with the directory indicated. It can be used to cancel a map spec- ified in the master map. For example, invoking the command in the following manner causes the entry in to be ignored: # automount /net -null Pattern Matching The ampersand (&) is expanded into the key field in a map wherever it appears. In the following example, the ampersand (&) expands to #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 program uses the asterisk to match any hostname other than #key mount_options location # oak &:/export/& * &:/home/& Environment Variables 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 environ- ment or can be explicitly defined with the command line option. Hierarchical Mounts You can mount different directories within an file system hierarchy from different servers. For example, if you are mounting the file sys- tem on your machine, you can mount the various subdirectories within from different servers. In the following example, the directories and are mounted from the machines host1, host2, host3, and host4 respectively. When the root of the hierarchy is referenced, the program mounts the whole hierarchy. /usr/local / -ro host1:/usr/local /bin -ro host2:/usr/local/bin /src -ro host2:/usr/local/src /tools -ro host2:/usr/src/tools Readability has been improved by splitting the entry into five lines and indenting the continuation lines. Options -m Ignores directory-mapname pairs listed in the Yellow Pages database. -n Disables dynamic mounts. Lookups intercepted by the daemon succeed when the target file system has been previously mounted. -T Traces all NFS requests received by the daemon. Information about the details of the request are expanded and sent to standard output. -v Logs status messages to the console. (Stands for ``verbose.'') -D name=value Defines an environment variable by assigning value to the variable. -f master-file Uses master-file for a list of initial directory to mapname pairs, ahead of the Yellow Pages map. If an entry exists in both master-file and that specified in master-file is used since it is read first. Similarly, entries on the command line take prece- dence over master-file entries. This technique can be used to replace entries in global maps with your own. -M mount-directory Uses mount-directory instead of the default, -tl duration Specifies a duration in seconds, that a file system is to remain mounted when not in use. The default is 5 minutes. -tm interval Specifies an interval in seconds, between attempts to mount a file system. The default is 30 seconds. -tw interval Specifies an interval in seconds, between attempts to unmount file systems that have exceeded their cached times. The default is 1 minute. -mount_options Specifies the mount options to be applied to all of the directories listed in mapname. If mount options are listed in the speci- fied map, they take precedence over these options. Sending the SIGTERM signal to the daemon causes it to unmount all file sys- tems that it has mounted, and to exit. Sending the SIGHUP signal to the 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 is unmounted by a command, should be forced to reread the system mount ta- ble. Restrictions Shell filename expansion does not apply to objects not currently mounted. Because is single-threaded, any request that is delayed by a slow or non-responding NFS server will delay all subsequent requests until the delayed request has been completed. Examples The following is a sample map: # # mount-point mapname mount-options # /net -hosts /home auto.indirect -rw /- auto.direct -ro,intr The following is a typical indirect map: # # key mount-options location # john merge:/home/merge/john mary stripe:/home/stripe/mary fred blur:/usr/staff/fred The following is a typical 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 The file system is mounted from the first server to respond to the request. reference -ro earl:/usr/src/ref fern:/usr/staff/ron/ref irv:/usr/backup/reference Files Directory where automounted file systems reside See Also mount(8), mount(8nfs), umount(8) Guide to the Network File System automount(8nfs)
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