Sys::Syslog(3pm) Perl Programmers Reference Guide Sys::Syslog(3pm)NAMESys::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 $mask_priority;
closelog;
DESCRIPTION
"Sys::Syslog" is an interface to the UNIX syslog(3) program. Call
"syslog()" with a string priority and a list of "printf()" args just
like syslog(3).
EXPORTS
"Sys::Syslog" exports the following "Exporter" tags:
· ":standard" exports the standard syslog(3) functions:
openlog closelog setlogmask syslog
· ":extended" exports the Perl specific functions for syslog(3):
setlogsock
· ":macros" exports the symbols corresponding to most of your sys‐
log(3) macros. See "CONSTANTS" for the supported constants and
their meaning.
By default, "Sys::Syslog" exports the symbols from the ":standard" tag.
FUNCTIONS
openlog($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. $facil‐
ity specifies the part of the system to report about, for example
"LOG_USER" or "LOG_LOCAL0": see your syslog(3) documentation for
the facilities available in your system. Facility can be given as a
string or a numeric macro.
This function will croak if it can't connect to the syslog daemon.
Note that "openlog()" now takes three arguments, just like open‐
log(3).
You should use openlog() before calling syslog().
Options
* "ndelay" - Open the connection immediately (normally, the con‐
nection is opened when the first message is logged).
* "nowait" - Don't wait for child processes that may have been
created while logging the message. (The GNU C library does not
create a child process, so this option has no effect on Linux.)
* "pid" - Include PID with each message.
Examples
Open the syslog with options "ndelay" and "pid", and with facility
"LOCAL0":
openlog($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 $mask_priority and
returns the old mask. If the mask argument is 0, the current log
mask is not modified. See "Levels" for the list of available lev‐
els.
Examples
Only log errors:
setlogmask(LOG_ERR);
Log critical messages, errors and warnings:
setlogmask(LOG_CRIT⎪LOG_ERR⎪LOG_WARNING);
setlogsock($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 "get‐
servbyname()". "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::Sys‐
log" was unable to find an appropriate an appropriate device.
SEE ALSOsyslog(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@comp‐
ton.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.
perl v5.8.8 2001-09-21 Sys::Syslog(3pm)
