ypxfr(8)ypxfr(8)NAMEypxfr - Transfer a Network Information Service (NIS) map from a NIS
server to the local host
SYNOPSIS
/var/yp/ypxfr [-a method] -f [-h host] -d [domain] [-c] [-C tid prog
ipadd port] mapname
OPTIONS
Specifies that NIS maps are to be stored in one of the following for‐
mats: 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. Other‐
wise, 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 ser‐
vice 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 nota‐
tion. 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.
DESCRIPTION
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 pos‐
sible 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.
RESTRICTIONS
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 data‐
base 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 sup‐
port for very large maps. NIS clients are not affected by these
enhancements.
EXAMPLES
The following is an example of the ypxfr command used with the btree
database routine to store NIS maps. ypxfr-a b group.byname
FILES
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.
SEE ALSO
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)
