ypxfr - Transfer a Network Information Service (NIS) map
from a NIS server to the local host
/var/yp/ypxfr [-a method] -f [-h host] -d [domain] [-c]
[-C tid prog ipadd port] mapname
Specifies that NIS maps are to be stored in one of the
following formats: btree -- Recommended when creating and
maintaining very large maps. dbm/ndbm -- For backward
compatibility. This is the default. hash -- A potentially
quicker method for managing small maps. Force the
transfer to occur even if the version at the MASTER is not
more recent than the local version. Do not send a "Clear
current map" request to the local ypserv process. This
option should be used if ypserv is not running locally at
the time when ypxfr is running. Otherwise, ypxfr will
report that it can not talk to the local ypserv, and the
transfer will fail. Get the map from host, regardless of
which map is the master. If host is not specified, ypxfr
will ask the NIS service for the name of the master, and
try to get the map from there. The host option can be a
name or an IP address in dotted numeric notation. Specify
a domain other than the default domain. 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 prog, listening on port port, and waiting for a
response to transaction tid.
The ypxfr command moves a NIS map, specified by the mapname
argument, to the local host by making use of normal
NIS services. It creates a temporary map in the directory
/var/yp/domain (which must already exist), fills it by
enumerating the map's entries, obtains the map parameters
(master and order number) and loads them into the map.
Once ypxfr has accomplished these tasks, it deletes any
old versions of the map and moves the temporary map to the
real mapname.
If ypxfr is run interactively, it writes its output to the
terminal. However, if it is invoked without a controlling
terminal, and if the log file /var/cluster/members/{memb}/yp/ypxfr.log
exists, it appends all its output
to that file. Since ypxfr is most often run from
/var/spool/cron/crontab/root, or by ypserv, you can use
the log file to retain a record of what was attempted, and
the results.
For consistency between servers, ypxfr should be run periodically
for every map in the NIS database. Different maps
change at different rates: the services.byname map may
not change for months at a time, for instance, and may
therefore be checked only once a day. It is possible that
mail.aliases or hosts.byname changes several times per
day. In such a case, it is appropriate to check hourly
for updates. A cron(8) entry should be used to perform
periodic updates automatically on NIS server machines
only. Rather than having a separate cron entry for each
map, commands can be grouped to update several maps in a
shell script. Examples (mnemonically named) are in
/var/yp: ypxfr_1perday, ypxfr_2perday, and ypxfr_1perhour.
They can serve as models for you to use.
See ypfiles(4) and ypserv(8) for an overview of NIS.
You must use the same database format for each map in a
domain. In addition, a server serving multiple NIS domains
must use the same database format for all domains.
Although a Tru64 UNIX NIS server that takes advantage of
btree files will be able to store very large maps, NIS
slave servers that lack this feature might have a much
smaller limit on the number of map entries they can handle.
It may not be possible to distribute very large maps
from a Tru64 UNIX NIS master server to a slave server that
lacks support for very large maps. NIS clients are not
affected by these enhancements.
The following is an example of the ypxfr command used with
the btree database routine to store NIS maps. ypxfr -a b
group.byname
The ypxfr log file. Each cluster member has its own copy.
Script to transfer maps once a day. Script to transfer
maps twice a day. Script to transfer maps once an hour.
The crontab script.
Commands: cron(8), yppush(8), ypserv(8), ypsetup(8)
Functions: btree(3), dbm(3), dbopen(3), hash(3), ndbm(3)
Files: ypfiles(4)
ypxfr(8)
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