ypxfr - transfer NIS database from remote server to local host

       Thorsten Kukuk <kukuk@linux-nis.org>

NIS Reference Manual                               12/31/2020                                           YPXFR(8)

ypxfr copies an NIS database from one NIS server to the local host by using the NIS service.  ypxfr is
       generally invoked by ypinit or by ypserv, when ypserv receives a map transfer request from yppush.  It
       creates a temporary map in the directory /var/yp/domain (this directory must already exist; domain is the
       default domainname for the local host), fills it by getting the map's entries and fetches the map
       parameters (master and order number). If the transfer was successful, the old version of the map will be
       deleted and the temporary copy will be moved into its place. Then, ypxfr will attempt to send a "clear
       current map" request to the local ypserv.

       If run interactively, ypxfr writes its output to stderr. However, if it is invoked without a controlling
       terminal, it will log the output to syslog.

       ypxfr is used primarily in environments where several NIS servers are in use. For all maps, you have a
       NIS master server, which maintains a canonical copy of the NIS map, and all the other servers, the NIS
       slaves, copy the new version of the map from the master whenever a update was made. Normally, you have
       one NIS master for all maps.

       In order to maintain consistency across all NIS servers, ypxfr can be run periodically in a cron job.
       Maps which change infrequently need only be updated once a day (preferably late at night when system
       usage is lowest), where those with frequent changes (such as passwd.byname and passwd.byuid) should be
       updated perhaps once every hour. Examples are in /usr/lib/yp: ypxfr_1perday, ypxfr_2perday, and
       ypxfr_1perhour.  They can serve as reasonable first cuts.

       Normally all updates should be propagated by yppush when /var/yp/Makefile is run on the NIS master
       server, however it is a good practice on large networks where possible outages could cause NIS slaves to
       fall out of sync with the master.

       /var/yp/[domainname]/[maps]

       ypxfr - transfer NIS database from remote server to local host

       The following options are supported:

       -f
           Force a map transfer. Normally, ypxfr will not transfer a map if it determines that the NIS master's
           copy is not newer than the existing copy already on the local host. This flag forces a transfer
           regardless of which server's version is more recent.

       -c
           Do not send a "clear current map" request to the ypserv process running on the local host. This flag
           is normally used when invoking ypxfr by ypinit or if ypserv is not running locally at the time you
           are running ypxfr.  Otherwise, ypxfr will complain that it cannot talk to the local ypserv, and the
           transfer will fail.

       -ddomain
           Specify a domain other than the default NIS domain.

       -hsourcehost
           Get the map from host, regardless of what the map says the master is. If host is not specified, ypxfr
           asks the NIS service for the name of the master, and tries to get the map from there. This option is
           used to insure that ypxfr only copies maps from the NIS master server.

       -ssourcedomain
           Specify a source domain from which to transfer a map that should be the same across domains.

       -Ctaskidprogam-numberhostport
           This option is only for use by ypserv.  When ypserv invokes ypxfr, it specifies that ypxfr should
           call back a yppush process at the host with IP address or name host, registered as program number
           progam-number, listening on port port, and waiting for a response to transaction taskid.

       -pyp_path
           Change the directory for the maps to yp_path/[domainname]/, the default is /var/yp/[domainname].

       mapname
           One or more names of the map to transfer.

ypserv(8), yppush(8), ypinit(8), cron(8), crontab(5)

/usr/lib/yp/ypxfr [-f] [-c] [-d targetdomain] [-h sourcehost] [-s sourcedomain]
                         [-C taskidprogram-numberhostport] [-p yp_path] mapname...