Config(3pm) User Contributed Perl Documentation Config(3pm)
NAME
Log::Log4perl::Config - Log4perl configuration file syntax
DESCRIPTION
In "Log::Log4perl", configuration files are used to describe how the
system's loggers ought to behave.
The format is the same as the one as used for "log4j", just with a few
perl-specific extensions, like enabling the "Bar::Twix" syntax instead
of insisting on the Java-specific "Bar.Twix".
Comment lines and blank lines (all whitespace or empty) are ignored.
Comment lines may start with arbitrary whitespace followed by one of:
# - Common comment delimiter
! - Java .properties file comment delimiter accepted by log4j
; - Common .ini file comment delimiter
Comments at the end of a line are not supported. So if you write
log4perl.appender.A1.filename=error.log #in current dir
you will find your messages in a file called "error.log #in current
dir".
Also, blanks between syntactical entities are ignored, it doesn't
matter if you write
log4perl.logger.Bar.Twix=WARN,Screen
or
log4perl.logger.Bar.Twix = WARN, Screen
"Log::Log4perl" will strip the blanks while parsing your input.
Assignments need to be on a single line. However, you can break the
line if you want to by using a continuation character at the end of the
line. Instead of writing
log4perl.appender.A1.layout=Log::Log4perl::Layout::SimpleLayout
you can break the line at any point by putting a backslash at the very
(!) end of the line to be continued:
log4perl.appender.A1.layout=\
Log::Log4perl::Layout::SimpleLayout
Watch out for trailing blanks after the backslash, which would prevent
the line from being properly concatenated.
Loggers
Loggers are addressed by category:
log4perl.logger.Bar.Twix = WARN, Screen
This sets all loggers under the "Bar::Twix" hierarchy on priority
"WARN" and attaches a later-to-be-defined "Screen" appender to them.
Settings for the root appender (which doesn't have a name) can be
accomplished by simply omitting the name:
log4perl.logger = FATAL, Database, Mailer
This sets the root appender's level to "FATAL" and also attaches the
later-to-be-defined appenders "Database" and "Mailer" to it.
Alternatively, the root logger can be addressed as "rootLogger":
log4perl.rootLogger = FATAL, Database, Mailer
The additivity flag of a logger is set or cleared via the "additivity"
keyword:
log4perl.additivity.Bar.Twix = 0|1
(Note the reversed order of keyword and logger name, resulting from the
dilemma that a logger name could end in ".additivity" according to the
log4j documentation).
Appenders and Layouts
Appender names used in Log4perl configuration file lines need to be
resolved later on, in order to define the appender's properties and its
layout. To specify properties of an appender, just use the "appender"
keyword after the "log4perl" intro and the appender's name:
# The Bar::Twix logger and its appender
log4perl.logger.Bar.Twix = DEBUG, A1
log4perl.appender.A1=Log::Log4perl::Appender::File
log4perl.appender.A1.filename=test.log
log4perl.appender.A1.mode=append
log4perl.appender.A1.layout=Log::Log4perl::Layout::SimpleLayout
This sets a priority of "DEBUG" for loggers in the "Bar::Twix"
hierarchy and assigns the "A1" appender to it, which is later on
resolved to be an appender of type "Log::Log4perl::Appender::File",
simply appending to a log file. According to the
"Log::Log4perl::Appender::File" manpage, the "filename" parameter
specifies the name of the log file and the "mode" parameter can be set
to "append" or "write" (the former will append to the logfile if one
with the specified name already exists while the latter would clobber
and overwrite it).
The order of the entries in the configuration file is not important,
"Log::Log4perl" will read in the entire file first and try to make
sense of the lines after it knows the entire context.
You can very well define all loggers first and then their appenders
(you could even define your appenders first and then your loggers, but
let's not go there):
log4perl.logger.Bar.Twix = DEBUG, A1
log4perl.logger.Bar.Snickers = FATAL, A2
log4perl.appender.A1=Log::Log4perl::Appender::File
log4perl.appender.A1.filename=test.log
log4perl.appender.A1.mode=append
log4perl.appender.A1.layout=Log::Log4perl::Layout::SimpleLayout
log4perl.appender.A2=Log::Log4perl::Appender::Screen
log4perl.appender.A2.stderr=0
log4perl.appender.A2.layout=Log::Log4perl::Layout::PatternLayout
log4perl.appender.A2.layout.ConversionPattern = %d %m %n
Note that you have to specify the full path to the layout class and
that "ConversionPattern" is the keyword to specify the printf-style
formatting instructions.
Configuration File Cookbook
Here's some examples of often-used Log4perl configuration files:
Append to STDERR
log4perl.category.Bar.Twix = WARN, Screen
log4perl.appender.Screen = Log::Log4perl::Appender::Screen
log4perl.appender.Screen.layout = \
Log::Log4perl::Layout::PatternLayout
log4perl.appender.Screen.layout.ConversionPattern = %d %m %n
Append to STDOUT
log4perl.category.Bar.Twix = WARN, Screen
log4perl.appender.Screen = Log::Log4perl::Appender::Screen
log4perl.appender.Screen.stderr = 0
log4perl.appender.Screen.layout = \
Log::Log4perl::Layout::PatternLayout
log4perl.appender.Screen.layout.ConversionPattern = %d %m %n
Append to a log file
log4perl.logger.Bar.Twix = DEBUG, A1
log4perl.appender.A1=Log::Log4perl::Appender::File
log4perl.appender.A1.filename=test.log
log4perl.appender.A1.mode=append
log4perl.appender.A1.layout = \
Log::Log4perl::Layout::PatternLayout
log4perl.appender.A1.layout.ConversionPattern = %d %m %n
Note that you could even leave out
log4perl.appender.A1.mode=append
and still have the logger append to the logfile by default, although
the "Log::Log4perl::Appender::File" module does exactly the opposite.
This is due to some nasty trickery "Log::Log4perl" performs behind the
scenes to make sure that beginner's CGI applications don't clobber the
log file every time they're called.
Write a log file from scratch
If you loathe the Log::Log4perl's append-by-default strategy, you can
certainly override it:
log4perl.logger.Bar.Twix = DEBUG, A1
log4perl.appender.A1=Log::Log4perl::Appender::File
log4perl.appender.A1.filename=test.log
log4perl.appender.A1.mode=write
log4perl.appender.A1.layout=Log::Log4perl::Layout::SimpleLayout
"write" is the "mode" that has "Log::Log4perl::Appender::File"
explicitly clobber the log file if it exists.
Configuration files encoded in utf-8
If your configuration file is encoded in utf-8 (which matters if you
e.g. specify utf8-encoded appender filenames in it), then you need to
tell Log4perl before running init():
use Log::Log4perl::Config;
Log::Log4perl::Config->utf( 1 );
Log::Log4perl->init( ... );
This makes sure Log4perl interprets utf8-encoded config files
correctly. This setting might become the default at some point.
SEE ALSO
Log::Log4perl::Config::PropertyConfigurator
Log::Log4perl::Config::DOMConfigurator
Log::Log4perl::Config::LDAPConfigurator (coming soon!)
LICENSE
Copyright 2002-2013 by Mike Schilli <m@perlmeister.com> and Kevin Goess
<cpan@goess.org>.
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
AUTHOR
Please contribute patches to the project on Github:
http://github.com/mschilli/log4perl
Send bug reports or requests for enhancements to the authors via our
MAILING LIST (questions, bug reports, suggestions/patches):
log4perl-devel@lists.sourceforge.net
Authors (please contact them via the list above, not directly): Mike
Schilli <m@perlmeister.com>, Kevin Goess <cpan@goess.org>
Contributors (in alphabetical order): Ateeq Altaf, Cory Bennett, Jens
Berthold, Jeremy Bopp, Hutton Davidson, Chris R. Donnelly, Matisse
Enzer, Hugh Esco, Anthony Foiani, James FitzGibbon, Carl Franks, Dennis
Gregorovic, Andy Grundman, Paul Harrington, Alexander Hartmaier David
Hull, Robert Jacobson, Jason Kohles, Jeff Macdonald, Markus Peter,
Brett Rann, Peter Rabbitson, Erik Selberg, Aaron Straup Cope, Lars
Thegler, David Viner, Mac Yang.
perl v5.36.0 2022-10-30 Config(3pm)
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