syslog

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

syslog — Genera un messaggio del system log

Descrizione

syslog(int $priorità, string $messaggio): int

syslog() genera un messaggio di log che viene distribuito dal logger di sistema. priorità è la combinazione della facility e del livello, valori utilizzabili sono riportati nella prossima sezione. L'argomento rimanente è il messaggio da inviare, eccetto i due caratteri %m che vengono sostituiti dalla stringa del messaggio di errore (strerror) corrispondente all'attuale valore di errno.

**Priorità **syslog()** (in ordine discendente)**
Costante	Descrizione
LOG_EMERG	sistema non utilizzabile
LOG_ALERT	azione da intraprendere immediatamente
LOG_CRIT	condizioni critiche
LOG_ERR	condizioni di errore
LOG_WARNING	condizioni di attenzione
LOG_NOTICE	condizione normale, ma significativa
LOG_INFO	messaggio di informazione
LOG_DEBUG	messaggio a livello di debug

Example #1 Uso di syslog()

<?php
define_syslog_variables();
// apre il syslog, include l'ID del processo, invia il
// log anche su standard error e fa uso di un meccanismo
// di logging defiito dall'utente
openlog("IlMioLog", LOG_PID | LOG_PERROR, LOG_LOCAL0);

// un po' di codice

if (client_autorizzato()) {
    // fa qualcosa
} else {
    // client non autorizzato!
    // logga il tentativo
    $accesso = date("Y/m/d H:i:s");
    syslog(LOG_WARNING,"Client non autorizzato: $accesso $REMOTE_ADDR ($HTTP_USER_AGENT)");
}

closelog();
?>

Per informazioni su come creare un gestore di log definito dall'utente, fare riferimento alla man page syslog.conf (5) di Unix. Ulteriori informazioni sulle facility di syslog e sulle sue opzioni possono essere trovate sulle macchine Unix nelle man page di syslog (3).

Su Windows NT, il servizio syslog è emulato usando Event Log.

Vedere anche define_syslog_variables(), openlog() e closelog().

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User Contributed Notes 16 notes

down

james dot ellis at gmail dot com ¶

17 years ago

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"

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stevekamerman at gmail dot com ¶

6 years ago

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

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OWM ¶

4 years ago

Syslog autodetects newline control characters and therefore splits the message by multiple lines. To prevent this behavior in PHP 7.3+ you can use undocumented (at this moment) ini setting:

<?php

ini_set('syslog.filter', 'raw');

# more info here: https://bugs.php.net/bug.php?id=77913

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Antonio Lobato ¶

14 years ago

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.

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rgagnon24 at gmail dot com ¶

5 years ago

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.

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huangyg11 at gmail dot com ¶

9 years ago

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");

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Anonymous ¶

3 years ago

There's no point to manually timestamp the message (as shown in docs' example) as all sane logging systems timestamp all entries by themselves.

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helly at php dot net ¶

17 years ago

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); };

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antoine dot leverve dot EXT at zodiacaerospace dot com ¶

8 years ago

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!

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daniele dot patoner at biblio dot unitn dot it ¶

21 years ago

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();
?>

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mavetju at chello dot nl ¶

23 years ago

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");

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-1

gregj at pdxperts dot com ¶

21 years ago

The message string sent to the log file is limited to 500 characters.

down

-2

dpreece at paradise dot net dot nz ¶

22 years ago

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

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-2

bb at lb-data dot co dot at ¶

25 years ago

In Windows NT, use the following values of priority:

1 = error,

6 = info

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-5

Torsten ¶

20 years ago

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.

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-4

rcgraves+php at brandeis dot edu ¶

24 years ago

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.

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