| Sys::Syslog - Perl interface to the UNIX syslog calls |
Sys::Syslog - Perl interface to the UNIX syslog(3) calls
This is the documentation of version 0.35
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();
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).
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.
$ident is prepended to every message. $logopt contains zero or
more of the options detailed below. $facility specifies the part
of the system to report about, for example LOG_USER or LOG_LOCAL0:
see Facilities for a list of well-known facilities, and your
syslog(3) documentation for the facilities available in your system.
Check SEE ALSO for useful links. Facility can be given as a string
or a numeric macro.
This function will croak if it can't connect to the syslog daemon.
Note that openlog() now takes three arguments, just like openlog(3).
Options
cons - This option is ignored, since the failover mechanism will drop
down to the console automatically if all other media fail.
ndelay - Open the connection immediately (normally, the connection is
opened when the first message is logged).
noeol - When set to true, no end of line character (\n) will be
appended to the message. This can be useful for some syslog daemons.
Added in Sys::Syslog 0.29.
nofatal - When set to true, openlog() and syslog() will only
emit warnings instead of dying if the connection to the syslog can't
be established. Added in Sys::Syslog 0.15.
nonul - When set to true, no NUL character (\0) will be
appended to the message. This can be useful for some syslog daemons.
Added in Sys::Syslog 0.29.
nowait - Don't wait for child processes that may have been created
while logging the message. (The GNU C library does not create a child
process, so this option has no effect on Linux.)
perror - Write the message to standard error output as well to the
system log. Added in Sys::Syslog 0.22.
pid - Include PID with each message.
Examples
Open the syslog with options ndelay and pid, and with facility LOCAL0:
openlog($name, "ndelay,pid", "local0");
Same thing, but this time using the macro corresponding to LOCAL0:
openlog($name, "ndelay,pid", LOG_LOCAL0);
$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 WARNING 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.
$mask_priority and
returns the old mask. If the mask argument is 0, the current log mask
is not modified. See Levels for the list of available levels.
You can use the LOG_UPTO() function to allow all levels up to a
given priority (but it only accept the numeric macros as arguments).
Examples
Only log errors:
setlogmask( LOG_MASK(LOG_ERR) );
Log everything except informational messages:
setlogmask( ~(LOG_MASK(LOG_INFO)) );
Log critical messages, errors and warnings:
setlogmask( LOG_MASK(LOG_CRIT)
| LOG_MASK(LOG_ERR)
| LOG_MASK(LOG_WARNING) );
Log all messages up to debug:
setlogmask( LOG_UPTO(LOG_DEBUG) );
openlog()
or syslog(). Returns true on success, undef on failure.
Being Perl-specific, this function has evolved along time. It can currently be called as follow:
setlogsock($sock_type)
setlogsock($sock_type, $stream_location) (added in Perl 5.004_02)
setlogsock($sock_type, $stream_location, $sock_timeout) (added in
Sys::Syslog 0.25)
setlogsock(\%options) (added in Sys::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 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. See also the host, port and timeout options.
"udp" - connect to a UDP socket, on the syslog/udp service.
See also the host, port and timeout options.
"inet" - connect to an INET socket, either TCP or UDP, tried in that
order. See also the host, port and timeout options.
"unix" - connect to a UNIX domain socket (in some systems a character
special device). The name of that socket is given by the path 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 the path 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 the path option,
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).
HP-UX is a system which uses such a named pipe.
"console" - send messages directly to the console, as for the "cons"
option of openlog().
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");
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 => $loghost });
Try the native, UDP socket then UNIX domain socket mechanisms:
setlogsock(["native", "udp", "unix"]);
Sys::Syslog and selected
by default, the use of the setlogsock() function is discouraged because
other mechanisms are less portable across operating systems. Authors of
modules and programs that use this function, especially its cargo-cult form
setlogsock("unix"), are advised to remove any occurrence of it unless they
specifically want to use a given mechanism (like TCP or UDP to connect to
a remote host).
The First Rule of Sys::Syslog is:
You do not call setlogsock.
The Second Rule of Sys::Syslog is:
You do not call setlogsock.
The Third Rule of Sys::Syslog is:
The program crashes, dies, calls closelog, the log is over.
The Fourth Rule of Sys::Syslog is: One facility, one priority.
The Fifth Rule of Sys::Syslog is: One log at a time.
The Sixth Rule of Sys::Syslog is:
No syslog before openlog.
The Seventh Rule of Sys::Syslog is: Logs will go on as long as they have to.
The Eighth, and Final Rule of Sys::Syslog is: If this is your first use of Sys::Syslog, you must read the doc.
An example:
openlog($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 setlogsocksetlogsock() an invalid value for $sock_type.
eventlog passed to setlogsock, but no Win32 API availablesetlogsock() 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 availablesyslog() failed to connect to the specified socket.
stream passed to setlogsock, but %s is not writablesetlogsock() to use a stream socket, but the given
path is not writable.
stream passed to setlogsock, but could not find any devicesetlogsock() 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 unavailablesetlogsock() to use a TCP socket, but the service
is not available on the system.
syslog: expecting argument %ssyslog() the indicated argument.
syslog: invalid level/facility: %ssyslog: too many levels given: %ssyslog: too many facilities given: %ssyslog: level must be givenudp passed to setlogsock, but udp service unavailablesetlogsock() to use a UDP socket, but the service
is not available on the system.
unix passed to setlogsock, but path not availablesetlogsock() to use a UNIX socket, but Sys::Syslog
was unable to find an appropriate an appropriate device.
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.*
0.29 5.16.*
0.32 5.18.*
0.33 5.20.*
0.33 5.22.*
the Log::Log4perl manpage - Perl implementation of the Log4j API
the Log::Dispatch manpage - Dispatches messages to one or more outputs
the Log::Report manpage - Report a problem, with exceptions and language support
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
FreeBSD documentation on syslog, https://www.freebsd.org/cgi/man.cgi?query=syslog
Solaris 11 documentation on syslog, https://docs.oracle.com/cd/E53394_01/html/E54766/syslog-3c.html
Mac OS X documentation on syslog, http://developer.apple.com/documentation/Darwin/Reference/ManPages/man3/syslog.3.html
IRIX documentation on syslog, http://nixdoc.net/man-pages/IRIX/man3/syslog.3c.html
AIX 5L 5.3 documentation on syslog, http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp
HP-UX 11i documentation on syslog, http://docs.hp.com/en/B2355-60130/syslog.3C.html
Tru64 documentation on syslog, http://nixdoc.net/man-pages/Tru64/man3/syslog.3.html
Stratus VOS 15.1, http://stratadoc.stratus.com/vos/15.1.1/r502-01/wwhelp/wwhimpl/js/html/wwhelp.htm
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
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.
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:
The source code is available on Git Hub: https://github.com/maddingue/Sys-Syslog/
Copyright (C) 1990-2012 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.
| Sys::Syslog - Perl interface to the UNIX syslog calls |