system commands gists

convert.rb

module FFMpeg
  class Convert
    attr_accessor :version, :total_time, :frame, :total_frames, :capturing,
                  :input_fps

    def initialize(input, output, options={})
      @input   = input
      @output  = output
      @options = options

      failure_msg = "FATAL:  cannot find ffmpeg command"
      failure_msg << " (#{ self.class.base_command })"

      self.class.system_command(failure_msg) do
        cmd = "#{ self.class.base_command } --version 2> /dev/null"
        system cmd
      end
    end

    def self.base_command
      ENV['FFMPEG'] || 'ffmpeg'
    end
    #...
end

server.rb

require 'escape'
require 'set'
require 'tempfile'
require 'sunspot/solr/java'
require 'sunspot/solr/installer'

module Sunspot
  module Solr
    class Server #:nodoc:
      
      # ...

      #
      # Start the sunspot-solr server. Bootstrap solr_home first,
      # if neccessary.
      #
      # ==== Returns
      #
      # Boolean:: success
      #
      def start
        bootstrap

        if File.exist?(pid_path)
          existing_pid = IO.read(pid_path).to_i
          begin
            Process.kill(0, existing_pid)
            raise(AlreadyRunningError, "Server is already running with PID #{existing_pid}")
          rescue Errno::ESRCH
            STDERR.puts("Removing stale PID file at #{pid_path}")
            FileUtils.rm(pid_path)
          end
        end
        fork do
          pid = fork do
            Process.setsid
            STDIN.reopen('/dev/null')
            STDOUT.reopen('/dev/null', 'a')
            STDERR.reopen(STDOUT)
            run
          end
          FileUtils.mkdir_p(pid_dir)
          File.open(pid_path, 'w') do |file|
            file << pid
          end
        end
      end

      #
      # Run the sunspot-solr server in the foreground. Boostrap
      # solr_home first, if neccessary.
      #
      # ==== Returns
      #
      # Boolean:: success
      #
      def run
        bootstrap

        command = ['java']
        command << "-Xms#{min_memory}" if min_memory
        command << "-Xmx#{max_memory}" if max_memory
        command << "-Djetty.port=#{port}" if port
        command << "-Djetty.host=#{bind_address}" if bind_address
        command << "-Dsolr.data.dir=#{solr_data_dir}" if solr_data_dir
        command << "-Dsolr.solr.home=#{solr_home}" if solr_home
        command << "-Djava.util.logging.config.file=#{logging_config_path}" if logging_config_path
        command << '-jar' << File.basename(solr_jar)
        FileUtils.cd(File.dirname(solr_jar)) do
          exec(Escape.shell_command(command))
        end
      end

      # ... 
  end
end

usage1.txt

ruby-1.9.2-p290 :002 > Executor::command("expr 5 / 0")
Executor::CommandFailure: Command "expr 5 / 0" failed with expr: division by zero

usage2.txt

ruby-1.9.2-p290 :011 > Executor::command("sleep 10 && echo 5") do |result|
ruby-1.9.2-p290 :012 >     puts "got result #{result}"
ruby-1.9.2-p290 :013?>   end
 => #<Thread:0x007fde40827a28 run> 
ruby-1.9.2-p290 :014 > sleep 10
got result 5
 => 10 
ruby-1.9.2-p290 :015 >