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ypfiles(4)
NAME
  ypfiles - Network Information Service (NIS) database and directory
  structure

DESCRIPTION
  The NIS database lookup service uses a database of dbm/ndbm, btree, or hash
  files in the /var/yp directory hierarchy.  A dbm/ndbm database consists of
  two files created by calls to the dbminit(3) function.  One has the
  filename extension .pag and the other has the filename extension .dir.  For
  instance, the database named hosts.byname, is implemented by the pair of
  files hosts.byname.pag and hosts.byname.dir.	A btree or hash database
  consists of a single file created by calls to the dbopen(3) function.	 A
  btree file has the filename extension .btree; a hash file has the extension
  .hash.

  A dbm/ndbm database served by NIS is called an NIS map.  A NIS domain is a
  named set of NIS maps.  Each NIS domain is implemented as a subdirectory of
  /var/yp containing the maps.	The number of NIS domains that can exist is
  unlimited.  Each domain can contain any number of maps.

  The NIS maps are not required by the NIS lookup service, although they may
  be required for the normal operation of other parts of the system.  The NIS
  lookup service serves all maps. If the map exists in a given domain and a
  client asks about it, NIS will serve it.  There is, however, a set of
  default maps that the NIS service serves.  The files representing these
  maps are listed in this description under Files.

  For a map to be accessible consistently, it must exist on all NIS servers
  that serve the domain.  To provide data consistency between the replicated
  maps, an entry to execute the ypxfr command periodically should be made in
  the /var/spool/cron/crontab/root file on each slave server.  More
  information on this topic is in ypxfr(8).  An entry in the
  /var/spool/cron/crontab/root file must not exist, either on a NIS master
  server or on a pure NIS client machine.

  The NIS maps should contain two distinguished key-value pairs.  The first
  is the key YP_LAST_MODIFIED, whose value is a 10-character ASCII order
  number.  The order number should be the UNIX time in seconds when the map
  was built.  The second key is YP_MASTER_NAME, with the name of the NIS
  master server as a value.  The makedbm(8) command generates both key-value
  pairs automatically.	A map that does not contain both key-value pairs can
  be served by the NIS, but the ypserv process will not be able to return
  values for ``Get order number'' or ``Get master name'' requests.  In
  addition, the values of these two keys are used by ypxfr(8) when it
  transfers a map from a master NIS server to a slave.

  Before they can be properly accessed, the NIS maps must be initially set up
  for both masters and slaves by using the ypsetup(8) function.	 Further, NIS
  maps must be generated and modified only at the master server location.
  Copies of the master server NIS maps can then be transferred to the slave
  servers using the ypxfr(8) function.	If ypxfr is unable to determine a
  map's location, or if it is unable to determine whether the local copy is
  more recent than the master copy, extra command line switches must be set
  when it is executed.

  After the server databases are set up, the contents of some maps may
  change.  In general, some ASCII source version of the database exists on
  the master.  This version should be changed with a standard text editor.
  The update is incorporated into the NIS map and is propagated from the
  master to the slaves by running /var/yp/Makefile. All maps must have
  entries in /var/yp/Makefile. If an NIS map is added, the /var/yp/Makefile
  must be edited to support the new map.  The makefile uses makedbm(8) to
  generate the NIS map on the master, and yppush(8) to propagate the changed
  map to the slaves.  The yppush(8) command is a client of the map ypservers,
  which lists all of the NIS servers.

FILES
  /var/yp/src/passwd
  /var/yp/src/group
  /var/yp/src/hosts
  /var/yp/src/networks
  /var/yp/src/services
  /var/yp/src/protocols
  /var/yp/src/netgroup

RELATED INFORMATION
  Commands: makedbm(8), rpcinfo(8), ypmake(8), yppoll(8), yppush(8),
  ypserv(8), ypsetup(8), ypxfr(8).

  Functions: btree(3), dbm(3), hash(3), ndbm(3).

Index for Section 4

Alphabetical listing for Y

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