Sys::Syslog - Perl interface to the UNIX syslog(3) calls
use Sys::Syslog; # all except setlogsock(), or: use Sys::Syslog qw(:DEFAULT setlogsock); # default set, plus setlogsock() use Sys::Syslog qw(:standard :macros); # standard functions, plus macros openlog $ident, $logopt, $facility; # don't forget this syslog $priority, $format, @args; $oldmask = setlogmask $mask_priority; closelog;
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
You can find a kind of FAQ in "THE RULES OF SYS::SYSLOG". Please read it before coding, and again before asking questions.
Sys::Syslog exports the following
:standard exports the standard
openlog closelog setlogmask syslog
:extended exports the Perl specific functions for
:macros exports the symbols corresponding to most of your
syslog(3) macros and the
LOG_MASK() functions. See "CONSTANTS" for the supported constants and their meaning.
Sys::Syslog exports the symbols from the
Opens the syslog.
$ident is prepended to every message.
$logopt contains zero or more of the options detailed below.
$facility specifies the part of the system to report about, for example
LOG_LOCAL0: see "Facilities" for a list of well-known facilities, and your
syslog(3) documentation for the facilities available in your system. Check "SEE ALSO" for useful links. Facility can be given as a string or a numeric macro.
This function will croak if it can't connect to the syslog daemon.
openlog() now takes three arguments, just like
You should use
openlog() before calling
cons - This option is ignored, since the failover mechanism will drop down to the console automatically if all other media fail.
ndelay - Open the connection immediately (normally, the connection is opened when the first message is logged).
nofatal - When set to true,
syslog() will only emit warnings instead of dying if the connection to the syslog can't be established.
nowait - Don't wait for child processes that may have been created while logging the message. (The GNU C library does not create a child process, so this option has no effect on Linux.)
perror - Write the message to standard error output as well to the system log.
pid - Include PID with each message.
Open the syslog with options
pid, and with facility
openlog($name, "ndelay,pid", "local0");
Same thing, but this time using the macro corresponding to
openlog($name, "ndelay,pid", LOG_LOCAL0);
$priority permits, logs
sprintf($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 the
eventlog mechanism, priorities
INFO are mapped to event type
If you didn't use
openlog() before using
syslog() will try to guess the
$ident by extracting the shortest prefix of
$format that ends in a
syslog("info", $message); # informational level syslog(LOG_INFO, $message); # informational level syslog("info|local0", $message); # information level, Local0 facility syslog(LOG_INFO|LOG_LOCAL0, $message); # information level, Local0 facility
Sys::Syslog version v0.07 and older passed the
$message as the formatting string to
sprintf() even when no formatting arguments were provided. If the code calling
syslog() might execute with older versions of this module, make sure to call the function as
syslog($priority, "%s", $message) instead of
syslog($priority, $message). This protects against hostile formatting sequences that might show up if $message contains tainted data.
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 the
LOG_UPTO() function to allow all levels up to a given priority (but it only accept the numeric macros as arguments).
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) );
Sets the socket type to be used for the next call to
syslog() and returns true on success,
undef on failure. The available mechanisms are:
"native" - use the native C functions from your
syslog(3) library (added in
"eventlog" - send messages to the Win32 events logger (Win32 only; added in
"tcp" - connect to a TCP socket, on the
syslogng/tcp service. If defined, the second parameter is used as a hostname to connect to.
"udp" - connect to a UDP socket, on the
syslog/udp service. If defined, the second parameter is used as a hostname to connect to, and the third parameter as the timeout used to check for UDP response.
"inet" - connect to an INET socket, either TCP or UDP, tried in that order. If defined, the second parameter is used as a hostname to connect to.
"unix" - connect to a UNIX domain socket (in some systems a character special device). The name of that socket is the second parameter or, if you omit the second parameter, the value returned by the
_PATH_LOG macro (if your system defines it), or /dev/log or /dev/conslog, whatever is writable.
"stream" - connect to the stream indicated by the pathname provided as the optional second parameter, or, if omitted, to /dev/conslog. For example Solaris and IRIX system may prefer
"stream" instead of
"pipe" - connect to the named pipe indicated by the pathname provided as the optional second parameter, or, if omitted, to the value returned by the
_PATH_LOG macro (if your system defines it), or /dev/log (added in
"console" - send messages directly to the console, as for the
"cons" option of
A reference to an array can also be passed as the first parameter. When this calling method is used, the array should contain a list of mechanisms which are attempted in order.
The default is to try
console. Under systems with the Win32 API,
eventlog will be added as the first mechanism to try if
Win32::EventLog is available.
Giving an invalid value for
Select the UDP socket mechanism:
Select the native, UDP socket then UNIX domain socket mechanisms:
setlogsock(["native", "udp", "unix"]);
Now that the "native" mechanism is supported by
Sys::Syslog and selected by default, the use of the
setlogsock() 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 form
setlogsock("unix"), are advised to remove any occurence of it unless they specifically want to use a given mechanism (like TCP or UDP to connect to a remote host).
Closes the log file and returns true on success.
The First Rule of Sys::Syslog is: You do not call
The Second Rule of Sys::Syslog is: You do not call
The Third Rule of Sys::Syslog is: The program crashes,
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
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.
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');
openlog("$program $$", 'ndelay', 'user'); syslog('notice', 'fooprogram: this is really done');
Example of use of
$! = 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');
LOG_AUDIT - audit daemon (IRIX); falls back to
LOG_AUTH - security/authorization messages
LOG_AUTHPRIV - security/authorization messages (private)
/dev/console output (FreeBSD); falls back to
LOG_CRON - clock daemons (cron and at)
LOG_DAEMON - system daemons without separate facility value
LOG_FTP - FTP daemon
LOG_KERN - kernel messages
LOG_INSTALL - installer subsystem (Mac OS X); falls back to
LOG_LAUNCHD - launchd - general bootstrap daemon (Mac OS X); falls back to
LOG_LFMT - logalert facility; falls back to
LOG_LOCAL7 - reserved for local use
LOG_LPR - line printer subsystem
LOG_MAIL - mail subsystem
LOG_NETINFO - NetInfo subsystem (Mac OS X); falls back to
LOG_NEWS - USENET news subsystem
LOG_NTP - NTP subsystem (FreeBSD, NetBSD); falls back to
LOG_RAS - Remote Access Service (VPN / PPP) (Mac OS X); falls back to
LOG_REMOTEAUTH - remote authentication/authorization (Mac OS X); falls back to
LOG_SECURITY - security subsystems (firewalling, etc.) (FreeBSD); falls back to
LOG_SYSLOG - messages generated internally by syslogd
LOG_USER (default) - generic user-level messages
LOG_UUCP - UUCP subsystem
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
Invalid argument passed to setlogsock
(F) You gave
setlogsock() an invalid value for
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
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, and
Sys::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, but
Sys::Syslog was unable to find an appropriate an appropriate device.
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
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
Syslogging with Perl, http://lexington.pm.org/meetings/022001.html
Windows Event Log, http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wes/wes/windows_event_log.asp
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>.
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.
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.
You can find documentation for this module with the perldoc command.
You can also look for information at:
AnnoCPAN: Annotated CPAN documentation
RT: CPAN's request tracker
Kobes' CPAN Search
Copyright (C) 1990-2008 by Larry Wall and others.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.