NAME
Sys::Syslog - Perl interface to the UNIX syslog(3) calls
VERSION
This is the documentation of version 0.34
SYNOPSIS
use Sys::Syslog; # all except setlogsock()
use Sys::Syslog qw(:standard :macros); # standard functions & macros
openlog($ident, $logopt, $facility); # don't forget this
syslog($priority, $format, @args);
$oldmask = setlogmask($mask_priority);
closelog();
DESCRIPTION
Sys::Syslog
is an interface to the UNIX syslog(3)
program. Call syslog()
with a string priority and a list of printf()
args just like syslog(3)
.
EXPORTS
Sys::Syslog
exports the following Exporter
tags:
:standard
exports the standardsyslog(3)
functions:openlog closelog setlogmask syslog
:extended
exports the Perl specific functions forsyslog(3)
:setlogsock
:macros
exports the symbols corresponding to most of yoursyslog(3)
macros and theLOG_UPTO()
andLOG_MASK()
functions. See "CONSTANTS" for the supported constants and their meaning.
By default, Sys::Syslog
exports the symbols from the :standard
tag.
FUNCTIONS
- openlog($ident, $logopt, $facility)
-
Opens the syslog.
$ident
is prepended to every message.$logopt
contains zero or more of the options detailed below.$facility
specifies the part of the system to report about, for exampleLOG_USER
orLOG_LOCAL0
: see "Facilities" for a list of well-known facilities, and yoursyslog(3)
documentation for the facilities available in your system. Check "SEE ALSO" for useful links. Facility can be given as a string or a numeric macro.This function will croak if it can't connect to the syslog daemon.
Note that
openlog()
now takes three arguments, just likeopenlog(3)
.You should use
openlog()
before callingsyslog()
.Options
cons
- This option is ignored, since the failover mechanism will drop down to the console automatically if all other media fail.ndelay
- Open the connection immediately (normally, the connection is opened when the first message is logged).noeol
- When set to true, no end of line character (\n
) will be appended to the message. This can be useful for some buggy syslog daemons.nofatal
- When set to true,openlog()
andsyslog()
will only emit warnings instead of dying if the connection to the syslog can't be established.nonul
- When set to true, noNUL
character (\0
) will be appended to the message. This can be useful for some buggy syslog daemons.nowait
- Don't wait for child processes that may have been created while logging the message. (The GNU C library does not create a child process, so this option has no effect on Linux.)perror
- Write the message to standard error output as well to the system log (added inSys::Syslog
0.22).pid
- Include PID with each message.
Examples
Open the syslog with options
ndelay
andpid
, and with facilityLOCAL0
:openlog($name, "ndelay,pid", "local0");
Same thing, but this time using the macro corresponding to
LOCAL0
:openlog($name, "ndelay,pid", LOG_LOCAL0);
- syslog($priority, $message)
- syslog($priority, $format, @args)
-
If
$priority
permits, logs$message
orsprintf($format, @args)
with the addition that%m
in $message or$format
is replaced with"$!"
(the latest error message).$priority
can specify a level, or a level and a facility. Levels and facilities can be given as strings or as macros. When using theeventlog
mechanism, prioritiesDEBUG
andINFO
are mapped to event typeinformational
,NOTICE
andWARNING
towarning
andERR
toEMERG
toerror
.If you didn't use
openlog()
before usingsyslog()
,syslog()
will try to guess the$ident
by extracting the shortest prefix of$format
that ends in a":"
.Examples
# informational level syslog("info", $message); syslog(LOG_INFO, $message); # information level, Local0 facility syslog("info|local0", $message); syslog(LOG_INFO|LOG_LOCAL0, $message);
- Note
-
Sys::Syslog
version v0.07 and older passed the$message
as the formatting string tosprintf()
even when no formatting arguments were provided. If the code callingsyslog()
might execute with older versions of this module, make sure to call the function assyslog($priority, "%s", $message)
instead ofsyslog($priority, $message)
. This protects against hostile formatting sequences that might show up if $message contains tainted data.
- setlogmask($mask_priority)
-
Sets the log mask for the current process to
$mask_priority
and returns the old mask. If the mask argument is 0, the current log mask is not modified. See "Levels" for the list of available levels. You can use theLOG_UPTO()
function to allow all levels up to a given priority (but it only accept the numeric macros as arguments).Examples
Only log errors:
setlogmask( LOG_MASK(LOG_ERR) );
Log everything except informational messages:
setlogmask( ~(LOG_MASK(LOG_INFO)) );
Log critical messages, errors and warnings:
setlogmask( LOG_MASK(LOG_CRIT) | LOG_MASK(LOG_ERR) | LOG_MASK(LOG_WARNING) );
Log all messages up to debug:
setlogmask( LOG_UPTO(LOG_DEBUG) );
- setlogsock()
-
Sets the socket type and options to be used for the next call to
openlog()
orsyslog()
. Returns true on success,undef
on failure.Being Perl-specific, this function has evolved along time. It can currently be called as follow:
setlogsock($sock_type)
setlogsock($sock_type, $stream_location)
(added in Perl 5.004_02)setlogsock($sock_type, $stream_location, $sock_timeout)
(added inSys::Syslog
0.25)setlogsock(\%options)
(added inSys::Syslog
0.28)
The available options are:
type
- equivalent to$sock_type
, selects the socket type (or "mechanism"). An array reference can be passed to specify several mechanisms to try, in the given order.path
- equivalent to$stream_location
, sets the stream location. Defaults to standard Unix location, or_PATH_LOG
.timeout
- equivalent to$sock_timeout
, sets the socket timeout in seconds. Defaults to 0 on all systems except Mac OS X where it is set to 0.25 sec.host
- sets the hostname to send the messages to. Defaults to the local host.port
- sets the TCP or UDP port to connect to. Defaults to the first standard syslog port available on the system.
The available mechanisms are:
"native"
- use the native C functions from yoursyslog(3)
library (added inSys::Syslog
0.15)."eventlog"
- send messages to the Win32 events logger (Win32 only; added inSys::Syslog
0.19)."tcp"
- connect to a TCP socket, on thesyslog/tcp
orsyslogng/tcp
service. See also thehost
,port
andtimeout
options."udp"
- connect to a UDP socket, on thesyslog/udp
service. See also thehost
,port
andtimeout
options."inet"
- connect to an INET socket, either TCP or UDP, tried in that order. See also thehost
,port
andtimeout
options."unix"
- connect to a UNIX domain socket (in some systems a character special device). The name of that socket is given by thepath
option or, if omitted, the value returned by the_PATH_LOG
macro (if your system defines it), /dev/log or /dev/conslog, whichever is writable."stream"
- connect to the stream indicated by thepath
option, or, if omitted, the value returned by the_PATH_LOG
macro (if your system defines it), /dev/log or /dev/conslog, whichever is writable. For example Solaris and IRIX system may prefer"stream"
instead of"unix"
."pipe"
- connect to the named pipe indicated by thepath
option, or, if omitted, to the value returned by the_PATH_LOG
macro (if your system defines it), or /dev/log (added inSys::Syslog
0.21). HP-UX is a system which uses such a named pipe."console"
- send messages directly to the console, as for the"cons"
option ofopenlog()
.
The default is to try
native
,tcp
,udp
,unix
,pipe
,stream
,console
. Under systems with the Win32 API,eventlog
will be added as the first mechanism to try ifWin32::EventLog
is available.Giving an invalid value for
$sock_type
willcroak
.Examples
Select the UDP socket mechanism:
setlogsock("udp");
Send messages using the TCP socket mechanism on a custom port:
setlogsock({ type => "tcp", port => 2486 });
Send messages to a remote host using the TCP socket mechanism:
setlogsock({ type => "tcp", host => $loghost });
Try the native, UDP socket then UNIX domain socket mechanisms:
setlogsock(["native", "udp", "unix"]);
- Note
-
Now that the "native" mechanism is supported by
Sys::Syslog
and selected by default, the use of thesetlogsock()
function is discouraged because other mechanisms are less portable across operating systems. Authors of modules and programs that use this function, especially its cargo-cult formsetlogsock("unix")
, are advised to remove any occurrence of it unless they specifically want to use a given mechanism (like TCP or UDP to connect to a remote host).
- closelog()
-
Closes the log file and returns true on success.
THE RULES OF SYS::SYSLOG
The First Rule of Sys::Syslog is: You do not call setlogsock
.
The Second Rule of Sys::Syslog is: You do not call setlogsock
.
The Third Rule of Sys::Syslog is: The program crashes, die
s, calls closelog
, the log is over.
The Fourth Rule of Sys::Syslog is: One facility, one priority.
The Fifth Rule of Sys::Syslog is: One log at a time.
The Sixth Rule of Sys::Syslog is: No syslog
before openlog
.
The Seventh Rule of Sys::Syslog is: Logs will go on as long as they have to.
The Eighth, and Final Rule of Sys::Syslog is: If this is your first use of Sys::Syslog, you must read the doc.
EXAMPLES
An example:
openlog($program, 'cons,pid', 'user');
syslog('info', '%s', 'this is another test');
syslog('mail|warning', 'this is a better test: %d', time);
closelog();
syslog('debug', 'this is the last test');
Another example:
openlog("$program $$", 'ndelay', 'user');
syslog('notice', 'fooprogram: this is really done');
Example of use of %m
:
$! = 55;
syslog('info', 'problem was %m'); # %m == $! in syslog(3)
Log to UDP port on $remotehost
instead of logging locally:
setlogsock("udp", $remotehost);
openlog($program, 'ndelay', 'user');
syslog('info', 'something happened over here');
CONSTANTS
Facilities
LOG_AUDIT
- audit daemon (IRIX); falls back toLOG_AUTH
LOG_AUTH
- security/authorization messagesLOG_AUTHPRIV
- security/authorization messages (private)LOG_CONSOLE
-/dev/console
output (FreeBSD); falls back toLOG_USER
LOG_CRON
- clock daemons (cron and at)LOG_DAEMON
- system daemons without separate facility valueLOG_FTP
- FTP daemonLOG_KERN
- kernel messagesLOG_INSTALL
- installer subsystem (Mac OS X); falls back toLOG_USER
LOG_LAUNCHD
- launchd - general bootstrap daemon (Mac OS X); falls back toLOG_DAEMON
LOG_LFMT
- logalert facility; falls back toLOG_USER
LOG_LOCAL0
throughLOG_LOCAL7
- reserved for local useLOG_LPR
- line printer subsystemLOG_MAIL
- mail subsystemLOG_NETINFO
- NetInfo subsystem (Mac OS X); falls back toLOG_DAEMON
LOG_NEWS
- USENET news subsystemLOG_NTP
- NTP subsystem (FreeBSD, NetBSD); falls back toLOG_DAEMON
LOG_RAS
- Remote Access Service (VPN / PPP) (Mac OS X); falls back toLOG_AUTH
LOG_REMOTEAUTH
- remote authentication/authorization (Mac OS X); falls back toLOG_AUTH
LOG_SECURITY
- security subsystems (firewalling, etc.) (FreeBSD); falls back toLOG_AUTH
LOG_SYSLOG
- messages generated internally by syslogdLOG_USER
(default) - generic user-level messagesLOG_UUCP
- UUCP subsystem
Levels
LOG_EMERG
- system is unusableLOG_ALERT
- action must be taken immediatelyLOG_CRIT
- critical conditionsLOG_ERR
- error conditionsLOG_WARNING
- warning conditionsLOG_NOTICE
- normal, but significant, conditionLOG_INFO
- informational messageLOG_DEBUG
- debug-level message
DIAGNOSTICS
Invalid argument passed to setlogsock
-
(F) You gave
setlogsock()
an invalid value for$sock_type
. eventlog passed to setlogsock, but no Win32 API available
-
(W) You asked
setlogsock()
to use the Win32 event logger but the operating system running the program isn't Win32 or does not provides Win32 compatible facilities. no connection to syslog available
-
(F)
syslog()
failed to connect to the specified socket. stream passed to setlogsock, but %s is not writable
-
(W) You asked
setlogsock()
to use a stream socket, but the given path is not writable. stream passed to setlogsock, but could not find any device
-
(W) You asked
setlogsock()
to use a stream socket, but didn't provide a path, andSys::Syslog
was unable to find an appropriate one. -
(W) You asked
setlogsock()
to use a TCP socket, but the service is not available on the system. syslog: expecting argument %s
-
(F) You forgot to give
syslog()
the indicated argument. syslog: invalid level/facility: %s
-
(F) You specified an invalid level or facility.
syslog: too many levels given: %s
-
(F) You specified too many levels.
syslog: too many facilities given: %s
-
(F) You specified too many facilities.
syslog: level must be given
-
(F) You forgot to specify a level.
-
(W) You asked
setlogsock()
to use a UDP socket, but the service is not available on the system. unix passed to setlogsock, but path not available
-
(W) You asked
setlogsock()
to use a UNIX socket, butSys::Syslog
was unable to find an appropriate an appropriate device.
HISTORY
Sys::Syslog
is a core module, part of the standard Perl distribution since 1990. At this time, modules as we know them didn't exist, the Perl library was a collection of .pl files, and the one for sending syslog messages with was simply lib/syslog.pl, included with Perl 3.0. It was converted as a module with Perl 5.0, but had a version number only starting with Perl 5.6. Here is a small table with the matching Perl and Sys::Syslog
versions.
Sys::Syslog Perl
----------- ----
undef 5.0.0 ~ 5.5.4
0.01 5.6.*
0.03 5.8.0
0.04 5.8.1, 5.8.2, 5.8.3
0.05 5.8.4, 5.8.5, 5.8.6
0.06 5.8.7
0.13 5.8.8
0.22 5.10.0
0.27 5.8.9, 5.10.1 ~ 5.14.2
0.29 5.16.0, 5.16.1
SEE ALSO
Other modules
Log::Log4perl - Perl implementation of the Log4j API
Log::Dispatch - Dispatches messages to one or more outputs
Log::Report - Report a problem, with exceptions and language support
Manual Pages
SUSv3 issue 6, IEEE Std 1003.1, 2004 edition, http://www.opengroup.org/onlinepubs/000095399/basedefs/syslog.h.html
GNU C Library documentation on syslog, http://www.gnu.org/software/libc/manual/html_node/Syslog.html
Solaris 10 documentation on syslog, http://docs.sun.com/app/docs/doc/816-5168/syslog-3c?a=view
Mac OS X documentation on syslog, http://developer.apple.com/documentation/Darwin/Reference/ManPages/man3/syslog.3.html
IRIX 6.5 documentation on syslog, http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi?coll=0650&db=man&fname=3c+syslog
AIX 5L 5.3 documentation on syslog, http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?topic=/com.ibm.aix.basetechref/doc/basetrf2/syslog.htm
HP-UX 11i documentation on syslog, http://docs.hp.com/en/B2355-60130/syslog.3C.html
Tru64 5.1 documentation on syslog, http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/V51_HTML/MAN/MAN3/0193____.HTM
Stratus VOS 15.1, http://stratadoc.stratus.com/vos/15.1.1/r502-01/wwhelp/wwhimpl/js/html/wwhelp.htm?context=r502-01&file=ch5r502-01bi.html
RFCs
RFC 3164 - The BSD syslog Protocol, http://www.faqs.org/rfcs/rfc3164.html -- Please note that this is an informational RFC, and therefore does not specify a standard of any kind.
RFC 3195 - Reliable Delivery for syslog, http://www.faqs.org/rfcs/rfc3195.html
Articles
Syslogging with Perl, http://lexington.pm.org/meetings/022001.html
Event Log
Windows Event Log, http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wes/wes/windows_event_log.asp
AUTHORS & ACKNOWLEDGEMENTS
Tom Christiansen <tchrist (at) perl.com> and Larry Wall <larry (at) wall.org>.
UNIX domain sockets added by Sean Robinson <robinson_s (at) sc.maricopa.edu> with support from Tim Bunce <Tim.Bunce (at) ig.co.uk> and the perl5-porters
mailing list.
Dependency on syslog.ph replaced with XS code by Tom Hughes <tom (at) compton.nu>.
Code for constant()
s regenerated by Nicholas Clark <nick (at) ccl4.org>.
Failover to different communication modes by Nick Williams <Nick.Williams (at) morganstanley.com>.
Extracted from core distribution for publishing on the CPAN by Sébastien Aperghis-Tramoni <sebastien (at) aperghis.net>.
XS code for using native C functions borrowed from Unix::Syslog
, written by Marcus Harnisch <marcus.harnisch (at) gmx.net>.
Yves Orton suggested and helped for making Sys::Syslog
use the native event logger under Win32 systems.
Jerry D. Hedden and Reini Urban provided greatly appreciated help to debug and polish Sys::Syslog
under Cygwin.
BUGS
Please report any bugs or feature requests to bug-sys-syslog (at) rt.cpan.org
, or through the web interface at http://rt.cpan.org/Public/Dist/Display.html?Name=Sys-Syslog. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
SUPPORT
You can find documentation for this module with the perldoc command.
perldoc Sys::Syslog
You can also look for information at:
Perl Documentation
MetaCPAN
Search CPAN
AnnoCPAN: Annotated CPAN documentation
CPAN Ratings
RT: CPAN's request tracker
The source code is available on Git Hub: https://github.com/maddingue/Sys-Syslog/
COPYRIGHT
Copyright (C) 1990-2012 by Larry Wall and others.
LICENSE
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.