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Sorry. In from version 2 to version 3, changed usage. see also


logging to file and standard output. require standard library only.


  • use standard lib only.
  • like Logger: see usage.
  • enabled or disabled by switching the output of the console and the logfile.


Add this line to your application's Gemfile:

gem 'tee_logger'

And then execute:

$ bundle

Or install it yourself as:

$ gem install tee_logger


require 'tee_logger'

# like options(logdev, shift_age, shift_size)
# options default value is
#   logdev     = './tee_logger.log'
#   shift_age  = 0
#   shift_size = 1_048_576
tl =

# let's logging
tl.debug 'hello'
tl.debug(:progname) { 'hello world' }
tl.progname = 'App'
tl.debug 'hello tee_logger'

# enable only when specified 'this message is console and logfile' 'this message is console only', :console 'this message is logfile only', :logfile

# log meassage indent 'hello'    # => 'hello' 'hello', 0 # => 'hello' 'hello', 2 # => '  hello'

# enabling and indent 'this message is console only', 2, :console 'this message is console only', :console, 2

# disable console output
tl.disable(:console) 'this message is logfile only'

# enable console output
tl.enable(:console) 'this message is logfile and console'

# disable logfile output
tl.disable(:logfile) 'this message is consle only'

# enable logfile output
tl.enable(:logfile) 'this message is logfile and console'

# disabe in block
tl.disable(:console) do 'this message is logfile only'
end 'this message is logfile and console'

# and others like Logger's
tl.debug? # => true  # => true
tl.warn?  # => true
tl.error? # => true
tl.fatal? # => true

tl.level # => 0
tl.level = Logger::INFO
tl.debug 'this message is not logging'

tl.formatter # => nil or Proc
tl.formatter = proc { |severity, datetime, progname, message| "#{severity}:#{message}" }

tl.datetime_format # => nil or Proc
tl.datetime_format = '%Y%m%d %H%M%S '


After checking out the repo, run bundle install to install dependencies. Then, run rake rspec to run the tests. You can also run budle exec pry -r ./lib/tee_logger for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.


The gem is available as open source under the terms of the MIT License.