class Daemons::PidFile


3. in the preconfigured directory /var/run (:system option for :dir_mode)
2. in a directory given by :dir (:normal option for :dir_mode)
as a daemon) resides (:script option for :dir_mode)
1. in a directory relative to the directory where the script (the one that is supposed to run
Daemons is configurable to store the Pid-Files relative to three different locations:
=== Where are the Pid-Files stored?
Each file just contains one line with the pid as string (for example 6432).
run at any time)
(Note that <number> is omitted if only one instance of the script can
<scriptname>.rb<number>.pid
Pid-Files generated by Daemons have to following format:
=== How does a Pid-File look like?
to exit when you issue a stop command.
to send them so called signals. Daemons uses the TERM signal to tell the script
Daemons needs the pid of the scripts that are currently running in the background
programs to find out the pid of a running script.
(pid) that is stored in a well-defined location of the filesystem thus allowing other
A Pid-File is a file containing the process identification number
=== What is a Pid-File?

def self.existing(path) 

def self.existing(path)
  new_instance = PidFile.allocate
  new_instance.instance_variable_set(:@path, path)
  def new_instance.filename
    @path
  end
  new_instance
end

def self.find_files(dir, progname, delete = false) 

def self.find_files(dir, progname, delete = false)
  files = Dir[File.join(dir, "#{progname}_num*.pid")]
  files = Dir[File.join(dir, "#{progname}.pid")] if files.size == 0
  files.delete_if { |f| not (File.file?(f) and File.readable?(f)) }
  if delete
    files.delete_if do |f|
      pid = File.open(f) { |h| h.read }.to_i
      rsl =  !Pid.running?(pid)
      if rsl
        puts "pid-file for killed process #{pid} found (#{f}), deleting."
        begin; File.unlink(f); rescue ::Exception; end
      end
      rsl
    end
  end
  files
end

def cleanup 

def cleanup
  File.delete(filename) if pid == Process.pid
end

def exist? 

def exist?
  File.exist? filename
end

def filename 

def filename
  File.join(@dir, "#{@progname}#{@number ? '_num' + @number.to_s : '' }.pid")
end

def initialize(dir, progname, multiple = false) 

def initialize(dir, progname, multiple = false)
  @dir = File.expand_path(dir)
  @progname = progname
  @multiple = multiple
  @number = nil
  @number = 0 if multiple
  if multiple
    while File.exist?(filename) && @number < 1024
      @number += 1
    end
    if @number >= 1024
      fail RuntimeException('cannot run more than 1024 instances of the application')
    end
  end
end

def pid 

def pid
  begin
    File.open(filename) do |f|
      p = f.gets.to_i
      return nil if p == 0  # Otherwise an invalid pid file becomes pid 0
      return p
    end
  rescue ::Exception
    return nil
  end
end

def pid=(p) 

def pid=(p)
  File.open(filename, 'w') do |f|
    f.chmod(0644)
    f.puts p   # Process.pid
  end
end

def zap 

def zap
  File.delete(filename)
end