要理解后台进程(Daemon)做了什么通常都更加的复杂，因为系统管理员与进程间并不进行直接交互。要检查后台进程（daemon）的工作状态，需要进行测试。例如：如果要测试Apache（web服务）的daemon是否有效，需要通过生成http请求的方式进行测试。
As a preventive operation, the administrator should regularly read the most relevant server logs. They can thus diagnose problems before they are even reported by disgruntled users. Indeed users may sometimes wait for a problem to occur repeatedly over several days before reporting it. In many cases, there are specific tools to analyze the contents of the larger log files. In particular, such utilities exist for web servers (such as
analog,
awstats,
webalizer for Apache), for FTP servers, for proxy/cache servers, for firewalls, for e-mail servers, for DNS servers, and even for print servers. Other tools, such as
logcheck (a software discussed in
第 14 章 安全), scan these files in search of alerts to be dealt with.
