Sys::Syslog

Section: Perl Programmers Reference Guide (3pm)
Updated: 2001-09-21
Index Return to Main Contents
 

NAME

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

VERSION

Version 0.13  

SYNOPSIS

    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

    setlogsock $sock_type;
    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. 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 words "pid", "ndelay", "nowait". The "cons" option is ignored, since the failover mechanism will drop down to the console automatically if all other media fail. $facility specifies the part of the system to report about, for example "LOG_USER" or "LOG_LOCAL0": see your syslog(3) documentation for the facilities available in your system. 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

*
"ndelay" - Open the connection immediately (normally, the connection is opened when the first message is logged).
*
"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.)
*
"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.

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

    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

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.

Examples

Only log errors:

    setlogmask(LOG_ERR);

Log critical messages, errors and warnings:

    setlogmask(LOG_CRIT|LOG_ERR|LOG_WARNING);

setlogsock($sock_type)
setlogsock($sock_type, $stream_location) (added in 5.004_02)
Sets the socket type to be used for the next call to "openlog()" or "syslog()" and returns true on success, "undef" on failure.

A value of "unix" will connect to the UNIX domain socket (in some systems a character special device) returned by the "_PATH_LOG" macro (if your system defines it), or /dev/log or /dev/conslog, whatever is writable. A value of 'stream' will connect to the stream indicated by the pathname provided as the optional second parameter. (For example Solaris and IRIX require "stream" instead of "unix".) A value of "inet" will connect to an INET socket (either "tcp" or "udp", tried in that order) returned by "getservbyname()". "tcp" and "udp" can also be given as values. The value "console" will send messages directly to the console, as for the "cons" option in the logopts in "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 sock_types which are attempted in order.

The default is to try "tcp", "udp", "unix", "stream", "console".

Giving an invalid value for $sock_type will croak.

closelog()
Closes the log file and return true on success.
 

EXAMPLES

    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');

    setlogsock('unix');
    openlog("$program $$", 'ndelay', 'user');
    syslog('notice', 'fooprogram: this is really done');

    setlogsock('inet');
    $! = 55;
    syslog('info', 'problem was %m'); # %m == $! in syslog(3)

    # Log to UDP port on $remotehost instead of logging locally
    setlogsock('udp');
    $Sys::Syslog::host = $remotehost;
    openlog($program, 'ndelay', 'user');
    syslog('info', 'something happened over here');

 

CONSTANTS

 

Facilities

*
"LOG_AUTH" - security/authorization messages
*
"LOG_AUTHPRIV" - security/authorization messages (private)
*
"LOG_CRON" - clock daemon (cron and at)
*
"LOG_DAEMON" - system daemons without separate facility value
*
"LOG_FTP" - ftp daemon
*
"LOG_KERN" - kernel messages
*
"LOG_LOCAL0" through "LOG_LOCAL7" - reserved for local use
*
"LOG_LPR" - line printer subsystem
*
"LOG_MAIL" - mail subsystem
*
"LOG_NEWS" - USENET news subsystem
*
"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.
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, like "LOG_KERN" (which is reserved to the kernel).
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.
 

SEE ALSO

syslog(3)

Syslogging with Perl, <http://lexington.pm.org/meetings/022001.html>  

AUTHOR

Tom Christiansen <tchrist@perl.com> and Larry Wall <larry@wall.org>.

UNIX domain sockets added by Sean Robinson <robinson_s@sc.maricopa.edu> with support from Tim Bunce <Tim.Bunce@ig.co.uk> and the "perl5-porters" mailing list.

Dependency on syslog.ph replaced with XS code by Tom Hughes <tom@compton.nu>.

Code for "constant()"s regenerated by Nicholas Clark <nick@ccl4.org>.

Failover to different communication modes by Nick Williams <Nick.Williams@morganstanley.com>.

Extracted from core distribution for publishing on the CPAN by Sebastien Aperghis-Tramoni <sebastien@aperghis.net>.  

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/NoAuth/ReportBug.html?Queue=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:

* 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/NoAuth/Bugs.html?Dist=Sys-Syslog>
* Search CPAN
<http://search.cpan.org/dist/Sys-Syslog>
 

LICENSE

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


 

Index

NAME
VERSION
SYNOPSIS
DESCRIPTION
EXPORTS
FUNCTIONS
EXAMPLES
CONSTANTS
Facilities
Levels
DIAGNOSTICS
SEE ALSO
AUTHOR
BUGS
SUPPORT
LICENSE

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