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 LXVIII. Network Functions安装这些函数作为 PHP 核心的一部分,无需被安装即可使用。运行时配置这些函数的行为受到全局配置文件 php.ini 的影响。 
   表格 1. Network Configuration Options | Name | Default | Changeable | 
|---|
 | define_syslog_variables | "0" | PHP_INI_ALL | 
 For further details and definition of the PHP_INI_* constants see
 ini_set() .
  以下是该配置选项的简要解释。 
  define_syslog_variables
   boolean
     Whether or not to define the various syslog variables (e.g. $LOG_PID,
     $LOG_CRON, etc.). Turning it off is a good idea performance-wise. At
     runtime, you can define these variables by calling
     define_syslog_variables().
    
预定义常量
这里列出的所有常量将作为 PHP 核心的一部分一直有效。
 表格 2. openlog() Options | Constant | Description | 
|---|
 | LOG_CONS | if there is an error while sending data to the system logger,
       write directly to the system console |  | LOG_NDELAY | open the connection to the logger immediately |  | LOG_ODELAY | (default) delay opening the connection until the first
       message is logged |  | LOG_NOWAIT |  |  | LOG_PERROR | print log message also to standard error |  | LOG_PID | include PID with each message | 
表格 3. openlog() Facilities | Constant | Description | 
|---|
 | LOG_AUTH | security/authorization messages (use LOG_AUTHPRIV instead
       in systems where that constant is defined) |  | LOG_AUTHPRIV | security/authorization messages (private) |  | LOG_CRON | clock daemon (cron and at) |  | LOG_DAEMON | other system daemons |  | LOG_KERN | kernel messages |  | LOG_LOCAL0 ... LOG_LOCAL7 | reserved for local use, these are not available in Windows |  | LOG_LPR | line printer subsystem |  | LOG_MAIL | mail subsystem |  | LOG_NEWS | USENET news subsystem |  | LOG_SYSLOG | messages generated internally by syslogd |  | LOG_USER | generic user-level messages |  | LOG_UUCP | UUCP subsystem | 
表格 4. syslog() Priorities (in descending order) | Constant | Description | 
|---|
 | LOG_EMERG | system is unusable |  | LOG_ALERT | action must be taken immediately |  | LOG_CRIT | critical conditions |  | LOG_ERR | error conditions |  | LOG_WARNING | warning conditions |  | LOG_NOTICE | normal, but significant, condition |  | LOG_INFO | informational message |  | LOG_DEBUG | debug-level message | 
表格 5. dns_get_record() Options | Constant | Description | 
|---|
 | DNS_A | IPv4 Address Resource |  | DNS_MX | Mail Exchanger Resource |  | DNS_CNAME | Alias (Canonical Name) Resource |  | DNS_NS | Authoritative Name Server Resource |  | DNS_PTR | Pointer Resource |  | DNS_HINFO | Host Info Resource (See IANA's
        Operating System Names
        for the meaning of these values) |  | DNS_SOA | Start of Authority Resource |  | DNS_TXT | Text Resource |  | DNS_ANY | Any Resource Record.  On most systems
        this returns all resource records, however
        it should not be counted upon for critical
	uses.  Try DNS_ALL instead. |  | DNS_AAAA | IPv6 Address Resource |  | DNS_ALL | Iteratively query the name server for
        each available record type. | 
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