FreeBSD Manual Pages
AMD(8) FreeBSD System Manager's Manual AMD(8) NAME amd -- automatically mount file systems SYNOPSIS amd -H amd [-F conf_file] amd [-nprvHS] [-a mount_point] [-c duration] [-d domain] [-k kernel-arch] [-l logfile] [-o op_sys_ver] [-t timeout.retransmit] [-w interval] [-x log-option] [-y YP-domain] [-C cluster-name] [-D option] [-F conf_file] [-O op_sys_name] [-T tag] [directory mapname [-map-options]] ... DESCRIPTION Amd is a daemon that automatically mounts file systems whenever a file or directory within that file system is accessed. File systems are automat- ically unmounted when they appear to be quiescent. Amd operates by attaching itself as an NFS server to each of the speci- fied directories. Lookups within the specified directories are handled by amd, which uses the map defined by mapname to determine how to resolve the lookup. Generally, this will be a host name, some file system infor- mation and some mount options for the given file system. In the first form depicted above, amd will print a short help string. In the second form, if no options are specified, or if the -F is used, amd will read configuration parameters from the file conf_file which defaults to /etc/amd.conf. The last form is described below. OPTIONS -a temporary-directory Specify an alternative location for the real mount points. The default is /.amd_mnt. -c duration Specify a duration, in seconds, that a looked up name remains cached when not in use. The default is 5 minutes. -d domain Specify the local domain name. If this option is not given the domain name is determined from the hostname. -k kernel-arch Specifies the kernel architecture. This is used solely to set the ${karch} selector. -l logfile Specify a logfile in which to record mount and unmount events. If logfile is the string syslog, the log messages will be sent to the system log daemon by syslog(3). The default syslog facility used is LOG_DAEMON. If you wish to change it, append its name to the log file name, delimited by a single colon. For example, if logfile is the string ``syslog:local7'' then amd will log mes- sages via syslog(3) using the LOG_LOCAL7 facility (if it exists on the system). -n Normalize hostnames. The name referred to by ${rhost} is normal- ized relative to the host database before being used. The effect is to translate aliases into ``official'' names. -o op_sys_ver Override the compiled-in version number of the operating system. Useful when the built in version is not desired for backward com- patibility reasons. For example, if the build in version is ``2.5.1'', you can override it to ``5.5.1'', and use older maps that were written with the latter in mind. -p Print PID. Outputs the process-id of amd to standard output where it can be saved into a file. -r Restart existing mounts. Amd will scan the mount file table to determine which file systems are currently mounted. Whenever one of these would have been auto-mounted, amd inherits it. -t timeout.retransmit Specify the NFS timeout interval, in tenths of a second, between NFS/RPC retries (for UDP only). The default is 0.8 seconds. The second value alters the retransmit counter, which defaults to 11 retransmissions. Both of these values are used by the kernel to communicate with amd. Useful defaults are supplied if either or both values are missing. Amd relies on the kernel RPC retransmit mechanism to trigger mount retries. The values of these parameters change the overall retry interval. Too long an interval gives poor interactive response; too short an interval causes excessive retries. -v Version. Displays version and configuration information on stan- dard error. -w interval Specify an interval, in seconds, between attempts to dismount file systems that have exceeded their cached times. The default is 2 minutes. -x options Specify run-time logging options. The options are a comma sepa- rated list chosen from: fatal, error, user, warn, info, map, stats, all. -y domain Specify an alternative NIS domain from which to fetch the NIS maps. The default is the system domain name. This option is ignored if NIS support is not available. -C cluster-name Specify an alternative HP-UX cluster name to use. -D option Select from a variety of debug options. Prefixing an option with the string no reverses the effect of that option. Options are cumulative. The most useful option is all. Since -D is only used for debugging other options are not docu- mented here: the current supported set of options is listed by the -v option and a fuller description is available in the pro- gram source. -F conf_file Specify an amd configuration file to use. See amd.conf(5) for description of this file's format. This configuration file is used to specify any options in lieu of typing many of them on the command line. The amd.conf file includes directives for every command line option amd has, and many more that are only avail- able via the configuration file facility. The configuration file specified by this option is processed after all other options have been processed, regardless of the actual location of this option on the command line. -H Print help and usage string. -O op_sys_name Override the compiled-in name of the operating system. Useful when the built in name is not desired for backward compatibility reasons. For example, if the build in name is ``sunos5'', you can override it to ``sos5'' and use older maps which were written with the latter in mind. -S Do not lock the running executable pages of amd into memory. To improve amd's performance, systems that support the plock(3) call, could lock the amd process into memory. This way there is less chance the operating system will schedule, page out, and swap the amd process as needed. This tends to improve amd's per- formance, at the cost of reserving the memory used by the amd process (making it unavailable for other processes). If this behavior is not desired, use the -S option. -T tag Specify a tag to use with amd.conf(5). All Map entries tagged with tag will be processed. Map entries that are not tagged are always processed. Map entries that are tagged with a tag other than tag will not be processed. FILES /.amd_mnt directory under which file systems are dynamically mounted /etc/amd.conf default configuration file CAVEATS Some care may be required when creating a mount map. Symbolic links on an NFS file system can be incredibly inefficient. In most implementations of NFS, their interpolations are not cached by the kernel and each time a symbolic link is encountered during a lookuppn translation it costs an RPC call to the NFS server. A large improvement in real-time performance could be gained by adding a cache somewhere. Replacing symlink(2) with a suitable incarnation of the auto-mounter results in a large real-time speedup, but also causes a large number of process context switches. A weird imagination is most useful to gain full advantage of all the fea- tures. SEE ALSO domainname(1), hostname(1), syslog(3), amd.conf(5), mtab(5), amq(8), mount(8), umount(8) Amd - The 4.4 BSD Automounter. http://www.am-utils.org/ HISTORY The amd utility first appeared in 4.4BSD. AUTHORS Jan-Simon Pendry <jsp@doc.ic.ac.uk>, Department of Computing, Imperial College, London, UK. Erez Zadok <ezk@am-utils.org>, Department of Computer Science, Columbia University, New York, USA. Other authors and contributors to am-utils are listed in the AUTHORS file distributed with am-utils. FreeBSD 6.2 April 19, 1994 FreeBSD 6.2
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | FILES | CAVEATS | SEE ALSO | HISTORY | AUTHORS
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=amd&sektion=8&manpath=FreeBSD+6.2-RELEASE>