(PHP 3, PHP 4, PHP 5)

syslog -- Generate a system log message


bool 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.

Table 1. syslog() Priorities (in descending order)

LOG_EMERGsystem is unusable
LOG_ALERTaction must be taken immediately
LOG_CRITcritical conditions
LOG_ERRerror conditions
LOG_WARNINGwarning conditions
LOG_NOTICEnormal, but significant, condition
LOG_INFOinformational message
LOG_DEBUGdebug-level message

Example 1. Using syslog()

// open syslog, include the process ID and also send
// the log to standard error, and use a user defined
// logging mechanism
openlog("myScriptLog", 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 $_SERVER[REMOTE_ADDR] ($_SERVER[HTTP_USER_AGENT])");

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.

Note: 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().