Sys::Syslog(3p) Perl Programmers Reference Guide Sys::Syslog(3p)
Sys::Syslog - Perl interface to the UNIX syslog(3) calls
Version 0.13
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 $mask_priority;
closelog;
"Sys::Syslog" is an interface to the UNIX syslog(3) program.
Call "syslog()" with a string priority and a list of
"printf()" args just like syslog(3).
"Sys::Syslog" exports the following "Exporter" tags:
+ ":standard" exports the standard syslog(3) functions:
openlog closelog setlogmask syslog
+ ":extended" exports the Perl specific functions for sys-
log(3):
setlogsock
+ ":macros" exports the symbols corresponding to most of
your syslog(3) macros. See "CONSTANTS" for the supported
constants and their meaning.
By default, "Sys::Syslog" exports the symbols from the
":standard" tag.
openlog($ident, $logopt, $facility)
Opens the syslog. $ident is prepended to every message.
$logopt contains zero or more of the words "pid", "nde-
lay", "nowait". The "cons" option is ignored, since the
failover mechanism will drop down to the console
automatically if all other media fail. $facility speci-
fies the part of the system to report about, for example
"LOG_USER" or "LOG_LOCAL0": see your syslog(3) documen-
tation for the facilities available in your system.
Facility can be given as a string or a numeric macro.
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This function will croak if it can't connect to the sys-
log daemon.
Note that "openlog()" now takes three arguments, just
like openlog(3).
You should use openlog() before calling syslog().
Options
* "ndelay" - Open the connection immediately (nor-
mally, the connection is opened when the first mes-
sage is logged).
* "nowait" - Don't wait for child processes that may
have been created while logging the message. (The
GNU C library does not create a child process, so
this option has no effect on Linux.)
* "pid" - Include PID with each message.
Examples
Open the syslog with options "ndelay" and "pid", and
with facility "LOCAL0":
openlog($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 facil-
ity. 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
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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
$message as the formatting string to "sprintf()"
even when no formatting arguments were provided. If
the code calling "syslog()" might execute with older
versions of this module, make sure to call the func-
tion as "syslog($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 mes-
sages 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
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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 $sock_type will croak.
closelog()
Closes the log file and return true on success.
openlog($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');
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
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+ "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
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.
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syslog: expecting argument %s
(F) You forgot to give "syslog()" the indicated argu-
ment.
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.
syslog(3)
Syslogging with Perl,
<http://lexington.pm.org/meetings/022001.html>
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>.
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Please report any bugs or feature requests to
"bug-sys-syslog at rt.cpan.org", or through the web inter-
face at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Sys-Syslog>.
I will be notified, and then you'll automatically be noti-
fied 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:
* 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>
This program is free software; you can redistribute it
and/or modify it under the same terms as Perl itself.
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