Deam - Simple daemon in ruby

2012-05-06T00:00:00+02:00

Today I will show you how to create simple daemon in Ruby.

I will be managing process called exec (which is self-explanatory).

STORE_FILE = "/tmp/deam_store"

loop do
  File.open(STORE_FILE, 'w') do |f|
    f.write(Time.now)
  end

  sleep 2
end

Rspec

To begin with start with simple tests, just to coverage basic scenario. I will start process, check it’s existence and stop it. Before doing this, I had to think a little bit about implementation (Deam::start, Deam::stop methods, Deam::PID_FILE constant which contain path of pid file).

To check if process with certain pid is running I use method found on stackoverflow.com.

require "./deam"

describe Deam do
  it "should start, check status, end proccess" do
    Deam.start; sleep 0.5

    File.exists?(Deam::PID_FILE).should be_true
    pid = File.read(Deam::PID_FILE).to_i
    expect { Process.getpgid(pid) }.should_not raise_error(Errno::ESRCH)

    Deam.stop; sleep 0.5

    File.exists?(Deam::PID_FILE).should_not be_true
    expect { Process.getpgid(pid) }.should raise_error(Errno::ESRCH)
  end
end

Implementation

This snippet shows the idea: few simple methods, getter and setter for pid file.

#!/usr/bin/env ruby

class Deam
  PID_FILE = "/tmp/deam.pid"
  EXEC_FILE = "./exec"

  class << self

    def start
      unless pid
        pipe = IO.popen(EXEC_FILE)
        self.pid = pipe.pid
      end
      status
    end

    def status
      if pid
        "Deamon is running."
      else
        "Deamon is not running."
      end
    end

    def stop
      if pid
        Process.kill("TERM", pid)
        self.pid = nil
      end
      status
    end

    def help
      "Available commands: 'deam start|status|stop'"
    end

    private

    def pid
      begin
        File.read(PID_FILE).to_i
      rescue
        nil
      end
    end

    def pid=(new_pid)
      if new_pid
        File.open(PID_FILE, 'w') do |f|
          f.write(new_pid)
        end
      else
        File.delete(PID_FILE)
      end
    end

  end

end

if __FILE__ == $0
  puts case ARGV[0]
    when "start"
      Deam.start
    when "status"
      Deam.status
    when "stop"
      Deam.stop
    else
      Deam.help
  end
end

Raxus - Easy file sharing

2012-04-29T00:00:00+02:00

Raxus is a gem that helps to easily transfer files or folders from one computer to another on a network. It’s a small Ruby script that facilitates transfer of data across networks and only requires the recipient of the files have a Web browser.

When you run command

raxus ~/some_data/ ~/image.jpg

your folder “some_data” and “image.jpg” will be compressed with zip, application will start a mini webserver (thin). Your files are available for download on adress YOUR_IP:5000.

Usage

Usage: raxus [options] file1 folder1 file2 ...
    -p, --port PORT
    -a, --address ADDRESS
    -l, --limit LIMIT                Set download limit.
    -h, --help                       Show this message

Install