NAME

Sys::Syslog - Perl interface to the UNIX syslog(3) calls

VERSION

This is the documentation of version 0.36

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 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.

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 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).
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);

syslog($priority, $message)

syslog($priority, $format, @args)

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 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);

Note: 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.

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 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) );

setlogsock()

Sets the socket type and options to be used for the next call to 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"]);

Note: 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 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, 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.

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 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

Levels

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

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, and Sys::Syslog was unable to find an appropriate one.
tcp passed to setlogsock, but tcp service unavailable: (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.
udp passed to setlogsock, but udp service unavailable: (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.

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.*
   0.29         5.16.*
   0.32         5.18.*
   0.33         5.20.*
   0.33         5.22.*

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

http://perldoc.perl.org/Sys/Syslog.html
MetaCPAN

https://metacpan.org/module/Sys::Syslog
Search CPAN

http://search.cpan.org/dist/Sys-Syslog/
AnnoCPAN: Annotated CPAN documentation

http://annocpan.org/dist/Sys-Syslog
CPAN Ratings

http://cpanratings.perl.org/d/Sys-Syslog
RT: CPAN's request tracker

http://rt.cpan.org/Dist/Display.html?Queue=Sys-Syslog

The source code is available on Git Hub: https://github.com/maddingue/Sys-Syslog/

COPYRIGHT

LICENSE

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

To install Sys::Syslog, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Sys::Syslog

CPAN shell

perl -MCPAN -e shell
install Sys::Syslog

For more information on module installation, please visit the detailed CPAN module installation guide.

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NAME

VERSION

SYNOPSIS

DESCRIPTION

EXPORTS

FUNCTIONS

THE RULES OF SYS::SYSLOG

EXAMPLES

CONSTANTS

Facilities

Levels

DIAGNOSTICS

HISTORY

SEE ALSO

Other modules

Manual Pages

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Articles

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BUGS

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COPYRIGHT

LICENSE

NAME

VERSION

SYNOPSIS

DESCRIPTION

EXPORTS

FUNCTIONS

THE RULES OF SYS::SYSLOG

EXAMPLES

CONSTANTS

Facilities

Levels

DIAGNOSTICS

HISTORY

SEE ALSO

Other modules

Manual Pages

RFCs

Articles

Event Log

AUTHORS & ACKNOWLEDGEMENTS

BUGS

SUPPORT

COPYRIGHT

LICENSE

Module Install Instructions