The London Perl and Raku Workshop takes place on 26th Oct 2024. If your company depends on Perl, please consider sponsoring and/or attending.


Log::ger::Layout::LTSV - Layout log message as LTSV


This document describes version 0.006 of Log::ger::Layout::LTSV (from Perl distribution Log-ger-Layout-LTSV), released on 2020-03-11.


 use Log::ger::Layout LTSV => (
     add_fields         => {key3 => 'value', key4 => 'value', ...},         # optional
     add_special_fields => {_date => 'Date_GMT', _host => 'Hostname', ...}, # optional
     delete_fields      => ['key1', 'key2', qr/some-regex/, ...],           # optional
 use Log::ger;

 # if you use it together with Log::ger::Format::None:
 log_warn({key1 => 'val1', key2 => 'val2', foo => 'bar', ...);

 # otherwise, using the standard formatter:
 log_warn("blah %s", ['some', 'data']);

The final message will be something like:

 _date:2017-06-28T14:08:22       foo:bar key3:value      key4:value


 _date:2017-06-28T14:08:22       message:blah ["some","data"]


This layouter allows you to log message as LTSV row. If you use Log::ger::Format::None, you can pass a hashref. Otherwise, the message will be put in message label. You can then delete keys then add additional fields/keys (including special fields, a la Log::ger::Layout::Pattern).


add_fields => hash

add_special_fields => hash

Known special fields:

 Category: Category of the logging event
 Class: Fully qualified package [or class] name of the caller
 Date_Local: Current date in ISO8601 format (YYYY-MM-DD<T>hh:mm:ss) (localtime)
 Date_GMT: Current date in ISO8601 format (YYYY-MM-DD<T>hh:mm:ss) (GMT)
 File: File where the logging event occurred
 Hostname: (if Sys::Hostname is available)
 Location: Fully qualified name of the calling method followed by the
   callers source the file name and line number between parentheses.
 Line: Line number within the file where the log statement was issued
 Message: The message to be logged
 Method: Method or function where the logging request was issued
 Level: Level ("priority") of the logging event
 PID: PID of the current process
 Elapsed_Start: Number of seconds elapsed from program start to logging event
 Elapsed_Last: Number of seconds elapsed from last logging event to current
   logging event
 Stack_Trace: stack trace of functions called

Unknown special fields will cause the layouter to die.



Regex or arrayref. When producing caller or stack trace information, will pass this to Devel::Caller::Util's caller() or callers().


Regex or arrayref. When producing caller or stack trace information, will pass this to Devel::Caller::Util's caller() or callers().


Please visit the project's homepage at


Source repository is at


Please report any bugs or feature requests on the bugtracker website

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.


More about LTSV format:




perlancar <>


This software is copyright (c) 2020, 2019, 2017 by

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.