11.3. 最主要的設定檔

The principal location for system configuration information is within /etc/rc.conf. This file contains a wide range of configuration information, principally used at system startup to configure the system. Its name directly implies this; it is configuration information for the rc* files.

An administrator should make entries in the rc.conf file to override the default settings from /etc/defaults/rc.conf. The defaults file should not be copied verbatim to /etc - it contains default values, not examples. All system-specific changes should be made in the rc.conf file itself.

A number of strategies may be applied in clustered applications to separate site-wide configuration from system-specific configuration in order to keep administration overhead down. The recommended approach is to place site-wide configuration into another file, such as /etc/rc.conf.site, and then include this file into /etc/rc.conf, which will contain only system-specific information.

As rc.conf is read by sh(1) it is trivial to achieve this. For example:

• rc.conf:

  	. /etc/rc.conf.site
  	hostname="node15.example.com"
  	network_interfaces="fxp0 lo0"
  	ifconfig_fxp0="inet 10.1.1.1"
  

• rc.conf.site:

  	defaultrouter="10.1.1.254"
  	saver="daemon"
  	blanktime="100"
  

The rc.conf.site file can then be distributed to every system using rsync or a similar program, while the rc.conf file remains unique.

Upgrading the system using sysinstall(8) or make world will not overwrite the rc.conf file, so system configuration information will not be lost.