Unicorn Config

unicorn.rb

require 'dotenv'

worker_processes Integer(ENV['WEB_CONCURRENCY'] || 3)
timeout 15
preload_app true

stderr_path "/srv/#{application}/shared/log/"ENV['RAILS_ENV']".log"
stdout_path "/srv/#{application}/shared/log/"ENV['RAILS_ENV']".log"
pid "/srv/#{application}/shared/tmp/pids/#{application}.pid"

before_fork do |server, worker|
  f = File.open("#{server.config[:pid]}.lock", 'w')
  exit unless f.flock(File::LOCK_SH)

  Signal.trap 'TERM' do
    puts 'Unicorn master intercepting TERM and sending myself QUIT instead'
    Process.kill 'QUIT', Process.pid
  end
end

after_fork do |server, worker|
  Signal.trap 'TERM' do
    puts 'Unicorn worker intercepting TERM and doing nothing. Wait for master to send QUIT'
  end
end

looks awesome. However, can you explain what
stderr_path ENV['UNICORN_LOG'] if ENV['UNICORN_LOG']
stdout_path ENV['UNICORN_LOG'] if ENV['UNICORN_LOG']
pid ENV['UNICORN_LOG'] if ENV['UNICORN_PID']
does? That is confusing to me.