ypxfr - transfer NIS database from remote server to local host
/usr/lib/yp/ypxfr [ -f ] [ -c ] [ -d target domain ]
[ -h source host ] [ -s source domain ]
[ -C taskid program-number ipaddr port ]
[ -p yp_path ] mapname ...
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 direc-
tory 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
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/Make-
file 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.
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 com-
plain that it cannot talk to the local ypserv, and the transfer
Specify a domain other than the default NIS domain.
-h source host
Get the map from host, regardless of what the map says the mas-
ter 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.
-s source domain
Specify a source domain from which to transfer a map that should
be the same across domains.
-C taskid progam-number ipaddr port
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 ipaddr, registered as program number
progam-number, listening on port port, and waiting for a
response to transaction taskid.
Change the directory for the maps to yp_path/[domainname]/, the
default is /var/yp/[domainname].
One or more names of the map to transfer.
ypserv(8), yppush(8), ypinit(8), cron(8), crontab(5)
Thorsten Kukuk <email@example.com>
YP Server August 2001 YPSERV(8)
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