openlog

(PHP 4, PHP 5, PHP 7, PHP 8)

openlog — Open connection to system logger

Description

openlog(string $prefix, int $flags, int $facility): true

openlog() opens a connection to the system logger for a program.

The use of openlog() is optional. It will automatically be called by syslog() if necessary, in which case prefix will default to false.

Parameters

prefix

The string prefix is added to each message.

flags

The flags argument is used to indicate what logging options will be used when generating a log message.

**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_PERROR`	print log message also to standard error
`LOG_PID`	include PID with each message

You can use one or more of these options. When using multiple options you need to OR them, i.e. to open the connection immediately, write to the console and include the PID in each message, you will use: LOG_CONS | LOG_NDELAY | LOG_PID

facility

The facility argument is used to specify what type of program is logging the message. This allows you to specify (in your machine's syslog configuration) how messages coming from different facilities will be handled.

**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

Note:
LOG_USER is the only valid log type under Windows operating systems

Return Values

Always returns true.

Changelog

Version	Description
8.2.0	The function now always returns `true`. Previously it returned `false` on failure.

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User Contributed Notes 2 notes

down

Nimja ¶

11 years ago

To those curious; switching between different facilities is NOT an issue. There is no apparent memory overhead (nor slowdown) by calling openlog multiple(12 * 10000) times.

Shown by this example:

<?php
$facilities = array(
    LOG_AUTH,
    LOG_AUTHPRIV,
    LOG_CRON,
    LOG_DAEMON,
    LOG_KERN,
    LOG_LOCAL0,
    LOG_LPR,
    LOG_MAIL,
    LOG_NEWS,
    LOG_SYSLOG,
    LOG_USER,
    LOG_UUCP,
);

for ($i = 0; $i < 10000; $i++) {
    foreach ($facilities as $facility) {
        openlog('test', LOG_PID, $facility);
        syslog(LOG_ERR, "This is a test: " . memory_get_usage(true));
    }
}
?>