php教程

syslog

(PHP 4, PHP 5, PHP 7)

syslog — Generate a system log message

说明

syslog ( int $priority , string $message ) : bool

syslog() generates a log message that will be distributed by the system logger.

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.

参数

priority

priority is a combination of the facility and the level. Possible values are:

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

message

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.

返回值

成功时返回 TRUE， 或者在失败时返回 FALSE。

范例

Example #1 Using syslog()

<?php
// 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']})");
}

closelog();
?>

注释

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.

参见

User Contributed Notes

rgagnon24 at gmail dot com 09-Feb-2019 04:39
This one had me going for a while when using LOG_ constants in another object, when developing on Windows, but deploying on Linux.

Windows evaluates some of the LOG_ constants to the same value, while LINUX does not.

The 8 constants and their differences on the platforms to be aware of:

Linux has these values as:
========================
LOG_EMERG = 0
LOG_ALERT = 1
LOG_CRIT = 2
LOG_ERR = 3
LOG_WARNING = 4
LOG_NOTICE = 5
LOG_INFO = 6
LOG_DEBUG = 7

While on Windows, you have:
==========================
LOG_EMERG = 1
LOG_ALERT = 1
LOG_CRIT = 1
LOG_ERR = 4
LOG_WARNING = 5
LOG_NOTICE = 6
LOG_INFO = 6
LOG_DEBUG = 6

So if you're setting LOG_WARNING in your code, Linux will use 4 as the priority while Windows will use 5.

This is not a bug in PHP on either platform, but a difference in the system header files that PHP compiles with.  Not really anything you can do, but be aware if you're wondering why your messages log at different priorities depending on the platform, this could be why.
stevekamerman at gmail dot com 24-Oct-2018 06:43
This function sends messages in BSD Syslog RFC 3164 format (https://tools.ietf.org/html/rfc3164).

To see the raw messages being sent by PHP to the logging socket, first stop your syslog/rsylsog/ng-syslog service, then listen to the logging socket with the netcat-openbsd package:

nc -U -l /dev/log

Now, log something from PHP:

<?php
syslog(LOG_LOCAL1|LOG_INFO, "Test from PHP");
?>

You will see the rfc3164 output from netcat:

<142>Oct 24 14:32:51 php: Test from PHP
antoine dot leverve dot EXT at zodiacaerospace dot com 21-Dec-2015 11:48
The documentation is incorrect when it says "Priorities (in descending order)", as the table that follows is actually in **ascending** order.

For example my output says:
LOG_ERR : 4
LOG_WARNING : 5
LOG_DEBUG : 6

An important difference, that caused me some pain!
huangyg11 at gmail dot com 11-May-2015 04:34
For those who want to simultaneously write to multiple syslog facilities :

syslog(LOG_INFO|LOG_LOCAL0, "message for local0");
syslog(LOG_INFO|LOG_LOCAL1, "message for local1");
Antonio Lobato 11-May-2010 01:57
A word of warning; if you use openlog() to ready syslog() and your Apache threads accept multiple requests, you *must* call closelog() if Apache's error log is configured to write to syslog.  Failure to do so will cause Apache's error log to write to whatever facility/ident was used in openlog.

Example, in httpd.conf you have:

ErrorLog syslog:local7

and in php you do:

<?php
openlog("myprogram", 0, LOG_LOCAL0);
syslog("My syslog message");
?>

From here on out, this Apache thread will write ErrorLog to local0 and under the process name "myprogram" and not httpd!  Calling closelog() will fix this.
james dot ellis at gmail dot com 02-Dec-2007 08:26
If anyone is wondering why their log messages are appearing in multiple log files, here is one answer applying to *nix systems:

If your syslog.conf looks like this (assuming you use LOG_LOCAL0 for web app logging) :

local0.info    /var/log/web/info.log

This will collect *all* messages of LOG_INFO level and higher, i.e everything except debug messages

Try this instead to ensure that only messages of the named log level go into the relevant log file:

local0.=info    /var/log/web/info.log

Additionally, you may like to add this to ensure your messages don't end up in generic log files like "messages"  "all" "syslog" and "debug":

local0.none    /var/log/messages
local0.none    /var/log/debug
etc

saves disk space among other things - more at "man syslog.conf"
helly at php dot net 13-Apr-2007 05:49
If you are using syslog-ng and want errors send to syslog then use ini setting "error_log = syslog" and add something like the following to your syslog-ng.conf:

destination php { file("/var/log/php.log" owner(root) group(devel) perm(0620)); };
log { source(src); filter(f_php); destination(php); };
adam _at_ lockdownnetworks _dot_ com 10-Apr-2007 06:32
Be aware when using syslog() that if you set the timezone of environment to be something other than the standard, syslog() may log the time to the log(s) with the wrong time zone information. For example:

<?php

openlog('mylog', LOG_PID | LOG_ODELAY,LOG_LOCAL4);

putenv('TZ=UTC');
syslog(LOG_INFO, 'UTC Log line');

putenv('TZ=US/Pacific');
syslog(LOG_INFO, 'US/Pacific Log line');

closelog();

?>

Viewing the /usr/log/messages log will display these two lines:

Apr 11 01:25:39 hostname mylog[1400]: UTC Log line
Apr 10 18:25:39 hostname mylog[1400]: US/Pacific Log line

Adam.
Torsten 23-Apr-2004 06:27
I had a problem trying to issue a syslog message with IIS 5.1 under Windows XP. The function call seemed to succeed, but the event viewer showed that no entry was made.
Finally I found out that the user account used for the webserver (IUSR_<Computername>) did not have enough permissions to issue syslog alerts. I changed this by adding this user to the Users group instead of only Guest.
daniele dot patoner at biblio dot unitn dot it 06-Nov-2003 11:00
This work for me, to redirect  logs to a separate syslog file

put this line in your /etc/syslog.conf :

local0.debug   /var/log/php.log

Then restart syslogd:

/etc/init.d/syslog restart

php example:

<?php
define_syslog_variables();
openlog("TextLog", LOG_PID, LOG_LOCAL0);

$data = date("Y/m/d H:i:s");
syslog(LOG_DEBUG,"Messagge: $data");

closelog();
?>
gregj at pdxperts dot com 28-Jul-2003 05:05
The message string sent to the log file is limited to 500 characters.
nospam \100 jraxis com (that's right!) 31-Mar-2002 08:32
This *does* actually goto the system log as configured in /etc/syslog.conf (such as /var/log/messages), it doesn't goto Apache's ErrorLog (such as /var/log/httpd/error_log). At least under my Debian Potato with Apache 1.3.23.

Use error_log() to be sure it gets into Apache's ErrorLog.
dpreece at paradise dot net dot nz 29-Jan-2002 04:08
To set up a custom log file via the syslog daemon (FreeBSD in this case)...

Add to /etc/syslog.conf a line that says all errors from the httpd process are to go to a file called (for example) /var/log/httpd-php.log

!httpd
*.*   {tab}   /var/log/httpd-php.log

Note the tab, being a tab character! Next create a blank file to be written to. I'm sure there are 1e+6 ways to do this, but I choose

# cat > httpd-php.log << EOF
? EOF

Finally find your syslog daemon and send it a sighup to inform it of the change:

# ps ax | grep syslogd
  133  ??  Ss     0:07.23 syslogd -s
# kill -1 133

Et voila! Php syslog calls will now arrive in /var/log/httpd-php.log
mavetju at chello dot nl 22-Jan-2001 06:11
With FreeBSD I can use: syslog(LOG_INFO,"test");

BSD/OS does not support this, I had to use the literal values for the priority (158: local3.info):
syslog(158,"test");
gherson at snet dot net 20-Dec-2000 01:09
Example of where to look for syslog's output:   /var/log/httpd/access_log
(on Red Hat Linux Secure Server v6.2).
rcgraves+php at brandeis dot edu 17-Feb-2000 12:51
For the-header-file-enabled:

man 3 syslog defines the priorities, but not the integer values. For that you'll need to read your system header file.

Let's suppose I want to log an informational message in the mail log (which happens to be true). The man page tells me I want LOG_MAIL|LOG_INFO. So I look in /usr/include/sys/syslog.h and find (this happens to be Linux, your system could be different):

#define LOG_INFO        6       /* informational */
#define LOG_MAIL        (2<<3)  /* mail system */

2<<3 means shift 3 bits left, which means multiply by 8. So I want 2*8 + 6 = 22. syslog(22,"this message will appear in the mail log"); And indeed it does.
bb at lb-data dot co dot at 08-Sep-1999 03:54
In Windows NT, use the following values of priority:
1 = error,
6 = info

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