ypfiles(5yp)															      ypfiles(5yp)

Name
       ypfiles - Yellow Pages data base and directory structure

Description
       The  Yellow  Pages  (YP) data base lookup service uses a data base of files in the directory hierarchy.	A data base consists of two files,
       created by calls to the library package.  One has the filename extension and the other has the filename extension For  instance,  the  data
       base named is implemented by the pair of files and

       A  data	base  served by YP is called a YP map.	A YP domain is a named set of YP maps.	Each YP domain is implemented as a subdirectory of
       containing the maps.  The number of YP domains that can exist is unlimited.  Each domain can contain any number of maps.

       The YP maps are not required by the YP lookup service, although they may be required for the normal operation of other parts of the system.
       The  YP	lookup	service serves all maps. If the map exists in a given domain and a client asks about it, YP will serve it.  There is, how-
       ever, a set of default maps that the YP 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 YP servers that serve the domain.	To provide data  consistency  between  the
       replicated  maps,  an  entry to execute the command periodically should be made in the file on each slave server.  More information on this
       topic is in An entry in the file must not exist, either on a YP master server or on a pure YP client machine.

       The YP 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 YP master server as a value.  The command generates both key-value pairs automatically.  A map that does not contain both  key-value
       pairs  can be served by the YP, but the process will not be able to return values for ``Get order number'' or ``Get master name'' requests.
       In addition, values of these two keys are used by when it transfers a map from a master YP server to a slave.

       Before they can be properly accessed, the YP maps must be initially set up for both masters and slaves by using the function.  Further,	YP
       maps must be generated and modified only at the master server location.	Copies of the master server YP maps can then be transferred to the
       slave servers using the function.  If 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  data  bases	are  set up, the contents of some maps may change.  In general, some ASCII source version of the data base
       exists on the master.  This version should be changed with a standard text editor.  The update is incorporated into the YP map and is prop-
       agated  from  the master to the slaves by running All maps must have entries in If a YP map is added, the must be edited to support the new
       map.  The makefile uses to generate the YP map on the master, and to propagate the changed map to the slaves.  The command is a	client	of
       the map ypservers, which lists all of the YP servers.

Files
See Also
       makedbm(8yp), rpcinfo(8nfs), ypmake(8yp), yppoll(8yp), yppush(8yp), ypserv(8yp), ypsetup(8yp), ypxfr(8yp)

																      ypfiles(5yp)