下列常量作为 PHP 核心的一部分总是可用的。
| 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 |
| 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 |
| 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 |
| 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. |