ypxfr(1Mnis)

ypxfr -- transfer NIS map from an NIS server to host

Synopsis

/usr/sbin/ypxfr [-c] [-f] [-d ypdomain] [-h host]
[-s ypdomain] [-C tid prog server] mapname

Description

The ypxfr command moves an Network Information Service (NIS) map in the default domain for the local host to the local host by making use of normal NIS services.

Options

ypxfr takes the following options:

-c: Do not send a ``Clear current map'' request to the local ypserv process. Use this flag if ypserv is not running locally at the time you are running ypxfr. Otherwise, ypxfr complains that it cannot talk to the local ypserv, and the transfer fails.
-f: Force the transfer to occur even if the version at the master is not more recent than the local version.
-C tid prog server: This option is used by ypserv only. When ypserv starts ypxfr, it specifies that ypxfr should call back a yppush process at the host server, registered as program number prog, and waiting for a response to transaction tid.
-d ypdomain: Specify a domain other than the default domain.
-h host: 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. host must be a name.
-s ypdomain: Specify a source domain from which to transfer a map that should be the same across domains.

Files

/var/yp/ypxfr.log: log file
/var/yp/YPMAPS: list of maps transferred by ypinit(1Mnis)
/usr/sbin/yp/ypxfr_1perday: cron(1M) script to run one transfer per day
/usr/sbin/yp/ypxfr_1perhour: script for hourly transfers of volatile maps
/var/yp/ypdomain: NIS domain
/usr/spool/cron/crontabs/root: the crontab file of the NIS administrator root with the appropriate privileges

Usage

ypxfr creates a temporary map in the directory /var/yp/ypdomain (this directory must already exist; ypdomain is the default domain for the local host), fills it by enumerating the map's entries, fetches the map parameters (master and order number), and loads them. ypxfr then deletes any old versions of the map and moves the temporary map to the real mapname.

If run interactively, ypxfr writes its output to the terminal. However, if it is started without a controlling terminal, and if the log file /var/yp/ypxfr.log exists, ypxfr appends all its output to that file. ypxfr is most often run from the crontab file of the NIS administrator with the appropriate privileges, or by ypserv. The log file can be used to retain a record of what was attempted, and what the results were.

For consistency between servers, ypxfr should be run periodically for every map in the NIS database. Different maps change at different rates: a map may not change for months at a time, for instance, and may therefore be checked only once a day. Some maps may change several times per day. In such a case, you may want to check hourly for updates. A crontab(1) entry can be used to perform periodic updates automatically. Rather than having a separate crontab entry for each map, you can group commands to update several maps in a shell script. Examples (mnemonically named) are in /usr/sbin/yp: ypxfr_1perday, and ypxfr_1perhour. They can serve as reasonable first cuts.

On a slave server, see the contents of the file /var/yp/YPMAPS for a list of maps that it obtained from the master server when it was first initialized using ypinit(1Mnis).

Refer to ypfiles(4nis) and ypserv(1Mnis) for an overview of the NIS service.

References

cron(1M), crontab(1), domainname(1Mnis), ypinit(1Mnis), ypserv(1Mnis), yppush(1Mnis), ypfiles(4nis)