Using Shell Scripts With cron and ypxfr

As an alternative to creating separate crontab entries for each map, you might prefer to have the root crontab command run a shell script that periodically updates all maps. Sample map-updating shell scripts are n the /usr/lib/netsvc/yp directory. The script names are ypxfr_1perday, ypxfr_1perhour, and ypxfr_2perday. You can modify or replace these shell scripts to fit your site requirements. Example 19-1 shows the default ypxfr_1perday shell script.

Example 19-1 ypxfr_1perday Shell Script

#! /bin/sh
#
# ypxfr_1perday.sh - Do daily yp map check/updates
PATH=/bin:/usr/bin:/usr/lib/netsvc/yp:$PATH
export PATH
# set -xv
ypxfr group.byname
ypxfr group.bygid
ypxfr protocols.byname
ypxfr protocols.bynumber
ypxfr networks.byname
ypxfr networks.byaddr
ypxfr services.byname
ypxfr ypservers

This shell script updates the maps once per day, if the root crontab is executed daily. You can also have scripts that update maps once a week, once a month, once every hour, and so forth, but be aware of the performance degradation implied in frequently propagating the maps.

Run the same shell scripts as root on each slave server configured for the NIS domain. Alter the exact time of execution from one server to another to avoid bogging down the master.

If you want to transfer the map from a particular slave server, use the -h machine option of ypxfr within the shell script. Here is the syntax of the commands you put in the script:

/usr/lib/netsvc/yp/ypxfr -h machine [ -c ] mapname

Where machine is the name of the server with the maps you want to transfer, and mapname is the name of the requested map. If you use the -h option without specifying a machine, ypxfr tries to get the map from the master server. If ypserv is not running locally at the time ypxfr is executed, you must use the -c flag so that ypxfr does not send a clear current map request to the local ypserver.

You can use the -s domain option to transfer maps from another domain to your local domain. These maps should be the same across domains. For example, two domains might share the same services.byname and services.byaddr maps. Alternatively, you can use rcp, or rdist for more control, to transfer files across domains.