sa-288上的问题，关于syslog的，没看懂，高手帮解释一下！

wondershow

Example A
192.9.200.1 host1 loghost
192.9.200.2 host2

Example B
192.9.200.1 host1
192.9.200.2 host2 loghost

Phase 1
When syslogd starts on boot, syslogd evaluates the /etc/hosts file
to check the IP address associated with the hostnamecompared to the
IP address associated with the loghost.
In Example A, host1 and loghost are both associated with IP address
192.9.200.1; therefore, syslogd runs the second command line,
/usr/ccs/bin/m4 -D LOGHOST that causes the m4 LOGHOST variable
to be evaluated as TRUE during the parsing of the /etc/sylog.conf
file.

In Example B, host1 is associated with IP address 192.9.200.1, while
host2 and loghost are both associated with IP address 192.9.200.2;
therefore, syslogd runs the first command line,
/usr/ccs/bin/m4 (no -D LOGHOST) that causes the m4 LOGHOST
variable to be evaluated as FALSE during the parsing of the
/etc/sylog.conf file.




为什么
In Example A, host1 and loghost are both associated with IP address
192.9.200.1; therefore, syslogd runs the second command line,
/usr/ccs/bin/m4 -D LOGHOST that causes the m4 LOGHOST variable
to be evaluated as TRUE during the parsing of the /etc/sylog.conf
file.


这个therefore的怎么成立？second command line 指什么？
192.9.200.2 host2   也是命令么？！！

哪位大虾为小弟指点迷津，谢谢！！！

climbmount

/etc/hosts中，loghost是本机则送本地文件，loghost非本机则通过网络送loghost，m4引擎就是这个意思。