Description
int 
syslog ( int priority, string message)
     syslog() generates a log message that will be
     distributed by the system logger.
     priority is a combination of the facility
     and the level, values for which are given in the next section.
     The remaining argument is the message to send, except that the
     two characters %m will be replaced by the
     error message string (strerror) corresponding to the present
     value of errno.
    
     
表格 1. 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 | 
     
| 例子 1. Using syslog() | 
<?phpdefine_syslog_variables();
 // open syslog, include the process ID and also send
 // the log to standard error, and use a user defined
 // logging mechanism
 openlog("myScripLog", LOG_PID | LOG_PERROR, LOG_LOCAL0);
 
 // some code
 
 if (authorized_client()) {
 // do something
 } else {
 // unauthorized client!
 // log the attempt
 $access = date("Y/m/d H:i:s");
 syslog(LOG_WARNING, "Unauthorized client: $access $REMOTE_ADDR ($HTTP_USER_AGENT)");
 }
 
 closelog();
 ?>
 | 
 | 
     For information on setting up a user defined log handler, see the
     
syslog.conf(5) Unix manual page.  More
     information on the syslog facilities and option can be found in the man
     pages for 
syslog(3) on Unix machines.
    
     On Windows NT, the syslog service is emulated using the Event
     Log.
    
注: 
      Use of LOG_LOCAL0 through
      LOG_LOCAL7 for the facility 
      parameter of openlog() is not available
      in Windows.
     
     See also define_syslog_variables(),
     openlog() and
     closelog().