Module: Daemonize

Included in:
Dctl::Daemon
Defined in:
lib/dctl/pidfile.rb,
lib/dctl/daemonize.rb

Defined Under Namespace

Classes: PidFile

Constant Summary collapse

VERSION = 
"0.1.1n"

Class Method Summary collapse

Class Method Details

.daemonize(stdin = '/dev/null', stdout = '/dev/null', stderr = '/dev/null', oldmode = true) ⇒ Object

This method causes the current running process to become a daemon



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# File 'lib/dctl/daemonize.rb', line 107

def daemonize(stdin='/dev/null', stdout='/dev/null', stderr='/dev/null', oldmode=true)
  stdin = File.expand_path stdin
  stdout = File.expand_path stdout
  stderr = File.expand_path stderr

  srand # Split rand streams between spawning and daemonized process
  safefork and exit # Fork and exit from the parent

  # Detach from the controlling terminal
  unless sess_id = Process.setsid
    raise SystemCallError, 'cannot detach from controlled terminal'
  end

  # Prevent the possibility of acquiring a controlling terminal
  if oldmode
    trap 'SIGHUP', 'IGNORE'
    safefork and exit
  end

  Dir.chdir "/"   # Release old working directory
  File.umask 0000 # Insure sensible umask

  # Make sure all file descriptors are closed
  ObjectSpace.each_object(IO) do |io|
    unless [STDIN, STDOUT, STDERR].include?(io)
      io.close rescue nil
    end
  end

  STDIN.reopen stdin             # Free file descriptors and
  STDOUT.reopen stdout, "a"      # point them somewhere sensible
  STDERR.reopen stderr, "a"      # STDOUT/STDERR should go to a logfile
  sess_id                        # Return value is mostly irrelevant
end

.safefork ⇒ Object

Try to fork if at all possible retrying every 5 sec if the maximum process limit for the system has been reached



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# File 'lib/dctl/daemonize.rb', line 95

def safefork
  begin
    fork
  rescue Errno::EWOULDBLOCK
    sleep 5
    retry
  end
end