Sys::Syslog - Perl interface to the UNIX syslog(3) calls
Version 0.26
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 syslog(3).
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 Exporter tags:
:standard exports the standard syslog(3) functions:
openlog closelog setlogmask syslog
:extended exports the Perl specific functions for syslog(3):
setlogsock
:macros exports the symbols corresponding to most of your syslog(3)
macros and the LOG_UPTO() and LOG_MASK() functions.
See "CONSTANTS" for the supported constants and their meaning.
By default, Sys::Syslog exports the symbols from the :standard tag.
Opens the syslog.
$ident is prepended to every message. $logopt contains zero or
more of the options detailed below. $facility specifies the part
of the system to report about, for example LOG_USER or LOG_LOCAL0:
see "Facilities" for a list of well-known facilities, and your
syslog(3) documentation for the facilities available in your system.
Check "SEE ALSO" for useful links. Facility can be given as a string
or a numeric macro.
This function will croak if it can't connect to the syslog daemon.
Note that openlog() now takes three arguments, just like openlog(3).
You should use openlog() before calling syslog().
Options
cons - This option is ignored, since the failover mechanism will drop
down to the console automatically if all other media fail.
ndelay - Open the connection immediately (normally, the connection is
opened when the first message is logged).
nofatal - When set to true, openlog() and syslog() will only
emit warnings instead of dying if the connection to the syslog can't
be established.
nowait - Don't wait for child processes that may have been created
while logging the message. (The GNU C library does not create a child
process, so this option has no effect on Linux.)
perror - Write the message to standard error output as well to the
system log.
pid - Include PID with each message.
Examples
Open the syslog with options ndelay and pid, and with facility LOCAL0:
openlog($name, "ndelay,pid", "local0");
Same thing, but this time using the macro corresponding to LOCAL0:
openlog($name, "ndelay,pid", LOG_LOCAL0);
If $priority permits, logs $message or sprintf($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 DEBUG and INFO are mapped to event type
informational, NOTICE and WARNIN to warning and ERR to
EMERG to error.
If you didn't use openlog() before using syslog(), 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);
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).
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) );
Sets the socket type to be used for the next call to
openlog() or 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 Sys::Syslog 0.15).
"eventlog" - send messages to the Win32 events logger (Win32 only;
added in Sys::Syslog 0.19).
"tcp" - connect to a TCP socket, on the syslog/tcp or 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 "unix".
"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 Sys::Syslog 0.21).
"console" - send messages directly to the console, as for the "cons"
option of openlog().
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 native, tcp, udp, unix, pipe, stream,
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 $sock_type will croak.
Examples
Select the UDP socket mechanism:
setlogsock("udp");
Select the native, UDP socket then UNIX domain socket mechanisms:
setlogsock(["native", "udp", "unix"]);
Sys::Syslog and selected
by default, the use of the setlogsock() function is discouraged because
other mechanisms are less portable across operating systems. Authors of
modules and programs that use this function, especially its cargo-cult form
setlogsock("unix"), are advised to remove any occurence of it unless they
specifically want to use a given mechanism (like TCP or UDP to connect to
a remote host).
The First Rule of Sys::Syslog is:
You do not call setlogsock.
The Second Rule of Sys::Syslog is:
You do not call setlogsock.
The Third Rule of Sys::Syslog is:
The program crashes, dies, calls closelog, the log is over.
The Fourth Rule of Sys::Syslog is: One facility, one priority.
The Fifth Rule of Sys::Syslog is: One log at a time.
The Sixth Rule of Sys::Syslog is:
No syslog before openlog.
The Seventh Rule of Sys::Syslog is: Logs will go on as long as they have to.
The Eighth, and Final Rule of Sys::Syslog is: If this is your first use of Sys::Syslog, you must read the doc.
An example:
openlog($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');
LOG_AUDIT - audit daemon (IRIX); falls back to LOG_AUTH
LOG_AUTH - security/authorization messages
LOG_AUTHPRIV - security/authorization messages (private)
LOG_CONSOLE - /dev/console output (FreeBSD); falls back to LOG_USER
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_USER
LOG_LAUNCHD - launchd - general bootstrap daemon (Mac OS X);
falls back to LOG_DAEMON
LOG_LFMT - logalert facility; falls back to LOG_USER
LOG_LOCAL0 through 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_DAEMON
LOG_NEWS - USENET news subsystem
LOG_NTP - NTP subsystem (FreeBSD, NetBSD); falls back to LOG_DAEMON
LOG_RAS - Remote Access Service (VPN / PPP) (Mac OS X);
falls back to LOG_AUTH
LOG_REMOTEAUTH - remote authentication/authorization (Mac OS X);
falls back to LOG_AUTH
LOG_SECURITY - security subsystems (firewalling, etc.) (FreeBSD);
falls back to LOG_AUTH
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
setlogsock() an invalid value for $sock_type.
eventlog passed to setlogsock, but no Win32 API available
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
setlogsock() to use a stream socket, but the given
path is not writable.
stream passed to setlogsock, but could not find any device
setlogsock() to use a stream socket, but didn't
provide a path, and Sys::Syslog was unable to find an appropriate one.
tcp passed to setlogsock, but tcp service unavailable
setlogsock() to use a TCP socket, but the service
is not available on the system.
syslog: expecting argument %s
syslog() the indicated argument.
syslog: invalid level/facility: %s
syslog: too many levels given: %s
syslog: too many facilities given: %s
syslog: level must be given
udp passed to setlogsock, but udp service unavailable
setlogsock() to use a UDP socket, but the service
is not available on the system.
unix passed to setlogsock, but path not available
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>.
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.
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.
perldoc Sys::Syslog
You can also look for information at:
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.