NAME

Log::Handler - A handler to log messages to different outputs.

SYNOPSIS

    use Log::Handler;

    my $log = Log::Handler->new();

    $log->add(File => {
        filename => 'file.log',
        maxlevel => 'debug',
        minlevel => 'warn',
        newline  => 1,
    });

    $log->alert("foo bar");

DESCRIPTION

This module is just a simple object oriented log handler and very easy to use. It's possible to define a log level for your programs and control the amount of informations that will be logged to one or more outputs. The outputs are different modules in the Log::Handler::Logger subtree and it's possible to extend it.

WHAT IS NEW, WHAT IS DEPRECATED

Backward compatibilities

As I re-designed the Log::Handler it was my wish to support the old style in version 0.38. The one exception is that the option redirect_to_stderr doesn't exist any more. In all other cases you can use all things from 0.38.

More than one output

Since version 0.38_01 the method add() is totaly new. With this method it's now possible to add output objects as much as you wish, each with an own level range and different other options. As example you can log the levels 0-4 (emerg-warn) to one object and the levels 4-7 (warn-debug) to another object. In addition you want to forward all log levels to a subroutine. That's possible.

Log::Handler::Logger

The main logic of Log::Handler is moved to Log::Handler::Logger. The Log::Handler just manage all logger objects and forward messages to it if the current log handler would log.

Placeholder

Placeholders are now available for the prefix in printf style. The old style of <--LEVEL--> is deprecated, instead you have to use %L as example. In addition a postfix option is available now. Take a look to the documentation of prefix and postfix.

Configuration file

Now it's possible to load the configuration from a file or define defaults. For this purpose I wrote Log::Handler::Config.

Kicked methods

The methods close(), get_prefix() and set_prefix() are not available any more.

Kicked options

rewrite_to_stderr.

trace()

The method trace() writes caller() informations to all logger by default. It's possible to disable this by set trace to 0.

Further releases

Extensions and further changes are planed. I hope I have enough time to implement my ideas as soon as possible!

METHODS

new()

Call new() to create a new log handler object.

    my $log = Log::Handler->new();

add()

Call add() to add a new logger.

There are different ways to add a new logger object to the handler. In the following example I show you one simple way:

    use Log::Handler;
    use Log::Handler::Logger::File;

    # the logger options (how to handle the file)
    my %logger_options = (
        timeformat      => '%Y/%m/%d %H:%M:%S',
        newline         => 1,
        prefix          => '%T [%L] %S: ',
        postfix         => '',
        maxlevel        => 'debug',
        minlevel        => 'emergency',
        die_on_errors   => 1,
        trace           => 1,
        debug           => 0,
        debug_mode      => 2,
        debug_skip      => 0,
    );

    # the options for the file
    my %file_options = (
        filename        => 'file.log',
        filelock        => 1,
        fileopen        => 1,
        reopen          => 1,
        mode            => 'append',
        autoflush       => 1,
        permissions     => '0660',
        utf8            => 1,
    );

    # we creating the objects
    my $log  = Log::Handler->new();
    my $file = Log::Handler::Logger::File->new( \%file_options );

    # now we add the file object to the handler and the logger options
    $log->add( $file => \%logger_options );

But it can be simplier! You can pass all options for the logger and for the file in one step. You just need to tell the handler what do you want to add.

    use Log::Handler;

    my %all_options = (%logger_options, %file_options);

    $log->add( file => \%all_options );

Further examples:

    $log->add( email => \%all_options );
    $log->add( forward => \%all_options );

Log level methods

There are eigth log level methods (thirteen with shortcuts):

debug()
info()
notice(), note()
warning(), warn()
error(), err()
critical(), crit()
alert()
emergency(), emerg()

debug() is the highest and emergency() or emerg() is the lowest log level. You can define the log level with the options maxlevel and minlevel.

The methods note(), warn(), err(), crit() and emerg() are just shortcuts.

Example:

If you set the option maxlevel to warning and minlevel to emergency then the levels emergency, alert, critical, error and warning will be logged.

The call of a log level method is very simple:

    $log->info("Hello World! How are you?");

Or maybe:

    $log->info("Hello World!", "How are you?");

Both calls would log

    Feb 01 12:56:31 [INFO] Hello World! How are you?

is_* methods

is_debug()
is_info()
is_notice(), is_note()
is_warning(), is_warn()
is_error(), is_err()
is_critical(), is_crit()
is_alert()
is_emergency(), is_emerg()

These thirteen methods could be very useful if you want to kwow if the current log level would output the message. All methods returns TRUE if the current set of minlevel and maxlevel would log the message and FALSE if not. Example:

    $log->debug(Dumper(\%hash));

This example would dump the hash in any case and pass it to the log handler, but that is not that what we really want!

    if ( $log->is_debug ) {
        $log->debug(Dumper(\%hash));
    }

Now we dump the hash only if the current log level would log it.

The methods is_note(), is_warn(), is_err(), is_crit() and is_emerg() are just shortcuts.

fatal(), is_fatal()

This are special methods that can be used for CRITICAL, ALERT and EMERGENCY messages. A lot of people like to use just the levels DEBUG, INFO, WARN, ERROR and FATAL so I though to implement this. You just have to set minlevel to critical, alert or emergency to use it.

trace()

This method is a special log level and very useful if you want to print caller() informations to all log files.

In contrast to the log level methods this method prints caller() informations to all log files in any case and you don't need to activate the debugger with the option debug. Example:

    my $log = Log::Handler->new( filename => \*STDOUT );
    $log->trace("caller informations:");

    Jun 05 21:20:32 [TRACE] caller informations
       CALL(2): package(main) filename(./log-handler-test.pl) line(22) subroutine(Log::Handler::trace) hasargs(1)
       CALL(1): package(Log::Handler) filename(/usr/local/share/perl/5.8.8/Log/Handler.pm) line(941) subroutine(Log::Handler::_write) hasargs(1)
       CALL(0): package(Log::Handler) filename(/usr/local/share/perl/5.8.8/Log/Handler.pm) line(1097) subroutine(Devel::Backtrace::new) hasargs(1) wantarray(0)

Maybe you like to print caller() informations to all log files if an unexpected error occurs.

    $SIG{__DIE__} = sub { $log->trace(@_) };

Take a look at the examples of the options debug, debug_mode and debug_skip for more informations.

errstr()

Call errstr() if you want to get the last error message. This is useful with die_on_errors. If you set die_on_errors to 0 then the handler wouldn't croak if a simple write operation fails. Set die_on_errors to control it yourself.

    use Log::Handler;

    my $log = Log::Handler->new();

    $log->add(file => {
        filename      => 'file.log',
        maxlevel      => 'info',
        mode          => 'append',
        die_on_errors => 0,
    });

    $log->info("Hello World!") or die $log->errstr;

    unless ( $log->info("Hello World!") ) {
        $error_string = $log->errstr;
    }

The exception is that the handler croaks in any case if the call of new() or add() fails because on missing or wrong settings!

config()

With this method it's possible to load your logger configuration from a file.

    $log->config(filename => 'file.conf');

Take a look into the documentation of Log::Handler::Config for more informations.

LOGGER OPTIONS

timeformat

You can set timeformat with a date and time format that will be coverted by POSIX::strftime. The default format is "%b %d %H:%M:%S" and looks like

    Feb 01 12:56:31

As example the format "%Y/%m/%d %H:%M:%S" would looks like

    2007/02/01 12:56:31

newline

This helpful option appends a newline to the log message if it not exist.

    0 - inactive (default)
    1 - active - appends a newline to the log message if not exist

prefix, postfix

It's possible to define a prefix and postfix for each message that will be logged to the log file. The prefix will be written before and the postfix after the message. Within the prefix and postfix it's possible to use different placeholders that will be replaced before the message goes to the log file.

The available placeholders are:

    %L  Log level
    %T  Timestamp
    %P  PID
    %H  Hostname
    %N  Newline
    %C  Caller - filename and line number where the logger was called
    %S  Script - the program name
    %M  Measurement - replaced with the time since the last call of the handler
    %m  The same as %M just 3 internal decimal places (0.001)

The default prefix is set to "%T [%L] ". The postfix is not defined by default. As example the following code

    $log->alert("foo bar");

would log by default

    Feb 01 12:56:31 [ALERT] foo bar

If you set prefix and postfix to

    prefix  => '%T foo %L bar '
    postfix => ' (%C)'

and call

    $log->info("baz");

then it would log

    Feb 01 12:56:31 foo INFO bar baz (script.pl, line 40)

Traces will be added after the postfix.

maxlevel and minlevel

With these options it's possible to set the log levels for your program. The log levels are:

    7 - debug
    6 - info
    5 - notice, note
    4 - warning, warn
    3 - error, err
    2 - critical, crit
    1 - alert
    0 - emergency, emerg

The levels note, err, crit and emerg are just shortcuts.

It's possible to set the log level as a string or as number. The default maxlevel is 4 and the default minlevel is 0.

Example: If maxlevel is set to 4 and minlevel to 0 then the levels emergency (emerg), alert, critical (crit) and error (err) are active and would be logged.

You can set both to 8 or nothing if you don't want to log any message.

die_on_errors

Set die_on_errors to 0 if you don't want that the handler croaks if normal operations fail.

    0 - will not die on errors
    1 - will die (e.g. croak) on errors

The exception is that the handler croaks in any case if the call of new() fails because on missing params or wrong settings.

trace

With this options it's possible to disable the tracing for a logger. By default this option is set to 1 and tracing is enabled.

debug

You can activate a simple debugger that writes caller() informations for each log level that would logged. The debugger is logging all defined values except hints and bitmask. Set debug to 1 to activate the debugger. The debugger is set to 0 by default.

debug_mode

There are two debug modes: line(1) and block(2) mode. The default mode is 1.

The block mode looks like this:

    use strict;
    use warnings;
    use Log::Handler;

    my $log = Log::Handler->new()

    $log->add(file => {
        filename   => '*STDOUT',
        maxlevel   => 'debug',
        debug      => 1,
        debug_mode => 1
    });

    sub test1 { $log->debug() }
    sub test2 { &test1; }

    &test2;

Output:

    Apr 26 12:54:11 [DEBUG] 
       CALL(4): package(main) filename(./trace.pl) line(15) subroutine(main::test2) hasargs(0)
       CALL(3): package(main) filename(./trace.pl) line(13) subroutine(main::test1) hasargs(0)
       CALL(2): package(main) filename(./trace.pl) line(12) subroutine(Log::Handler::__ANON__) hasargs(1)
       CALL(1): package(Log::Handler) filename(/usr/local/share/perl/5.8.8/Log/Handler.pm) line(713) subroutine(Log::Handler::_write) hasargs(1)
       CALL(0): package(Log::Handler) filename(/usr/local/share/perl/5.8.8/Log/Handler.pm) line(1022) subroutine(Devel::Backtrace::new) hasargs(1) wantarray(0)

The same code example but the debugger in block mode would looks like this:

       debug_mode => 2

Output:

   Apr 26 12:52:17 [DEBUG] 
      CALL(4):
         package     main
         filename    ./trace.pl
         line        15
         subroutine  main::test2
         hasargs     0
      CALL(3):
         package     main
         filename    ./trace.pl
         line        13
         subroutine  main::test1
         hasargs     0
      CALL(2):
         package     main
         filename    ./trace.pl
         line        12
         subroutine  Log::Handler::__ANON__
         hasargs     1
      CALL(1):
         package     Log::Handler
         filename    /usr/local/share/perl/5.8.8/Log/Handler.pm
         line        681
         subroutine  Log::Handler::_write
         hasargs     1
      CALL(0):
         package     Log::Handler
         filename    /usr/local/share/perl/5.8.8/Log/Handler.pm
         line        990
         subroutine  Devel::Backtrace::new
         hasargs     1
         wantarray   0

debug_skip

This option let skip the caller() informations the count of debug_skip.

    debug_skip => 2

    Apr 26 12:55:07 [DEBUG] 
       CALL(2): package(main) filename(./trace.pl) line(16) subroutine(main::test2) hasargs(0)
       CALL(1): package(main) filename(./trace.pl) line(14) subroutine(main::test1) hasargs(0)
       CALL(0): package(main) filename(./trace.pl) line(13) subroutine(Log::Handler::__ANON__) hasargs(1)

EXAMPLES

Simple example to log all level to one log file:

    use Log::Handler;

    my $log = Log::Handler->new();

    $log->add(file => {
       filename => 'file1.log',
       mode     => 'append',
       newline  => 1,
       maxlevel => 7,
       minlevel => 0
    });

    $log->debug("this is a debug message");
    $log->info("this is a info message");
    $log->notice("this is a notice");
    $log->note("this is a notice as well");
    $log->warning("this is a warning");
    $log->warn("this is a warning as well");
    $log->error("this is a error message");
    $log->err("this is a error message as well");
    $log->critical("this is a critical message");
    $log->crit("this is a critical message as well");
    $log->alert("this is a alert message");
    $log->emergency("this is a emergency message");
    $log->emerg("this is a emergency message as well");

Would log

    Feb 01 12:56:31 [DEBUG] this is a debug message
    Feb 01 12:56:31 [INFO] this is a info message
    Feb 01 12:56:31 [NOTICE] this is a notice
    Feb 01 12:56:31 [NOTICE] this is a notice as well
    Feb 01 12:56:31 [WARNING] this is a warning
    Feb 01 12:56:31 [WARNING] this is a warning
    Feb 01 12:56:31 [ERROR] this is a error message
    Feb 01 12:56:31 [ERROR] this is a error message as well
    Feb 01 12:56:31 [CRITICAL] this is a critical message
    Feb 01 12:56:31 [CRITICAL] this is a critial message as well
    Feb 01 12:56:31 [ALERT] this is a alert message
    Feb 01 12:56:31 [EMERGENCY] this is a emergency message
    Feb 01 12:56:31 [EMERGENCY] this is a emergency message as well

Different log files:

    use Log::Handler;

    # create the log handler object
    my $log = Log::Handler->new;

    $log->add(file => {
        filename => 'debug.log',
        mode     => 'append',
        maxlevel => 7,
        minlevel => 7,
        trace    => 1,
    });

    $log->add(file => {
        filename => 'common.log',
        mode     => 'append',
        maxlevel => 6,
        minlevel => 5,
        trace    => 0,
    });

    $log->add(file => {
        filename => 'error.log',
        mode     => 'append',
        maxlevel => 4,
        minlevel => 0,
        trace    => 1,
    });

    # log to debug.log
    $log->debug("this is a debug message");

    # log to common.log
    $log->info("this is a info message");
    $log->notice("this is a notice");
    $log->note("this is a notice as well");

    # log to error.log
    $log->warning("this is a warning");
    $log->warn("this is a warning as well");
    $log->error("this is a error message");
    $log->err("this is a error message as well");
    $log->critical("this is a critical message");
    $log->crit("this is a critical message as well");
    $log->alert("this is a alert message");
    $log->emergency("this is a emergency message");
    $log->emerg("this is a emergency message as well");

    # force caller() informations just to error.log and debug.log
    $log->trace("this message goes to all log files");

Just a notice:

    use Log::Handler;

    my $log = Log::Handler->new();

    $log->add(file => {
       filename   => '/var/run/pid-file1',
       mode       => 'trunc',
       maxlevel   => 5,
       minlevel   => 5,
       prefix     => '',
       timeformat => ''
    });

    $log->note($$);

Would truncate /var/run/pid-file1 and write just the pid to the logfile.

Selfmade prefix:

    use Log::Handler;

    my $log = Log::Handler->new();

    $log->add(file => {
       filename => "${progname}.log",
       mode     => 'append',
       maxlevel => 6,
       newline  => 1,
       prefix   => "%H[%P] [%L] %S: "
    });

    $log->info("Hello World!");
    $log->warning("There is something wrong!");

Would log:

    Feb 01 12:56:31 hostname[8923] [INFO] progname: Hello world
    Feb 01 12:56:31 hostname[8923] [WARNING] progname: There is something wrong!

is_* example:

    use Log::Handler;
    use Data::Dumper;

    my $log = Log::Handler->new();

    $log->add(file => {
       filename   => 'file1.log',
       mode       => 'append',
       maxlevel   => 4,
    });

    my %hash = (foo => 1, bar => 2);

    $log->debug("\n".Dumper(\%hash))
        if $log->is_debug();

Would NOT dump %hash to the $log object!

EXTENSIONS

Do you want write further extensions? There are just some requirements!

Logger objects should provide a new() and a write() method.

Config plugins should provide a get_config() routine.

Take a look into the source or write me a mail if you have questions.

PREREQUISITES

Prerequisites for all modules:

    Carp
    Config::General
    Devel::Backtrace
    Fcntl
    Net::SMTP
    Params::Validate
    POSIX
    Time::HiRes
    Sys::Hostname
    UNIVERSAL::require

Just for the test suite:

    File::Spec
    Test::More

EXPORTS

No exports.

REPORT BUGS

Please report all bugs to <jschulz.cpan(at)bloonix.de>.

AUTHOR

Jonny Schulz <jschulz.cpan(at)bloonix.de>.

QUESTIONS

Do you have any questions or ideas?

MAIL: <jschulz.cpan(at)bloonix.de>

IRC: irc.perl.org#perl

If you send me a mail then add Log::Handler into the subject.

TODO

    * Log::Handler::Logger::DBI
    * Log::Handler::Logger::Socket

COPYRIGHT

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

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

To install Log::Handler, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Log::Handler

CPAN shell

perl -MCPAN -e shell
install Log::Handler

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

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NAME

SYNOPSIS

DESCRIPTION

WHAT IS NEW, WHAT IS DEPRECATED

Backward compatibilities

More than one output

Log::Handler::Logger

Placeholder

Configuration file

Kicked methods

Kicked options

trace()

Further releases

METHODS

new()

add()

Log level methods

is_* methods

fatal(), is_fatal()

trace()

errstr()

config()

LOGGER OPTIONS

timeformat

newline

prefix, postfix

maxlevel and minlevel

die_on_errors

trace

debug

debug_mode

debug_skip

EXAMPLES

Simple example to log all level to one log file:

Different log files:

Just a notice:

Selfmade prefix:

is_* example:

EXTENSIONS

PREREQUISITES

EXPORTS

REPORT BUGS

AUTHOR

QUESTIONS

TODO

COPYRIGHT

DISCLAIMER OF WARRANTY

Module Install Instructions