ypfiles(4)                          CLIX                          ypfiles(4)



  NAME

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

  DESCRIPTION

    The Network Information Service (NIS) network lookup service uses a
    database of ndbm files in the /etc/yp directory hierarchy.  An ndbm
    database consists of two files, created by calls to the dbm library
    package.  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.
    An ndbm database served by the 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 /etc/yp containing the map.  Any number of NIS domains can exist.  Each
    may contain any number of maps.

    No maps are required by the NIS lookup service itself, although they may
    be required for the normal operation of other parts of the system.  There
    is not a list of maps which NIS serves - if the map exists in a given
    domain, and a client asks about it, the NIS serves it.  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 run the ypxfr command periodically should be made in the crontab file
    on each server.  More information on this topic is in ypxfr(8).

    NIS maps should contain two distinguished key-value pairs.  The first is
    the key NIS_LAST_MODIFIED, having as a value a ten-character ASCII order
    number.  The order number should be the CLIX time (in seconds) when the
    map was built.  The second key is NIS_MASTER_NAME, with the name of the
    NIS master server as a value.  The makedbm 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 is not able to
    return values for ``Get order number'' or ``Get master name'' requests.
    In addition, values of these two keys are used by ypxfr when it transfers
    a map from a master NIS server to a slave.  If ypxfr cannot figure out
    where to get the map, or if it is unable to determine whether the local
    copy is more recent than the copy at the master, extra command line flags
    must be set when it is run.

    NIS maps must be generated and modified only at the master server.  They
    are copied to the slaves using ypxfr to avoid potential byte-ordering
    problems among NIS servers running on machines with different
    architectures, and to minimize the amount of disk space required for the
    ndbm files.  The NIS database can be initially set up for both masters and
    slaves by using the ypinit command.

    After the server databases are set up, it is probable that the contents of
    some maps will change.  In general, some ASCII source version of the
    database exists on the master, and it is changed with a standard text



  2/94 - Intergraph Corporation                                              1

  ypfiles(4)                          CLIX                          ypfiles(4)



    editor.  The update is incorporated into the NIS map and is propagated
    from the master to the slaves by running /etc/yp/Makefile.  All supplied
    maps have entries in /etc/yp/Makefile.  If an NIS map is added, this file
    should be edited to support the new map.  The makefile uses makedbm to
    generate the NIS map on the master, and yppush to propagate the changed
    map to the slaves.  The yppush command is a client of the map ypservers,
    which lists all the NIS servers (see yppush(8)).

  RELATED INFORMATION

    Commands:  makedbm(8), ypinit(8), ypmake(8), ypxfr(8), yppush(8),
    yppoll(8), ypserv(8), rpcinfo(8)










































  2                                              Intergraph Corporation - 2/94