Railsから複数行のLinuxコマンドを非同期で実行させる ref: http://qiita.com/t_oginogin/items/10da086566a092845af4

daemon_spawn.rb

:
def self.start(daemon, args) #:nodoc:
  :
  fork do
    Process.setsid
    exit if fork
    open(daemon.pid_file, 'w') { |f| f << Process.pid }
    :
  end
  :
end
:

file0.txt

$ echo "sleep 100000" > ~/bin/test_command
$ chmod +x ~/bin/test_command

file10.txt

$ ps aux | grep sleep
ogi              3954   0.0  0.0  2432784    504 s001  R+    4:17PM   0:00.00 grep sleep
ogi              3838   0.0  0.0  2432764    468   ??  S     4:08PM   0:00.00 sleep 100000

file11.txt

$ ps -p 4043 -o "pgid"
 PGID
 2947

file12.txt

$ kill -- -2947

file13.txt

`kill -TERM -2947`

file15.txt

$ rails runner JobTask.execute
"4308"

file16.txt

$ ps aux | grep test_command
ogi              4317   0.0  0.0  2423368    216 s001  R+    4:45PM   0:00.00 grep test_command
ogi              4308   0.0  0.0  2442580    568   ??  S     4:44PM   0:00.00 sh -c test_command > test.log 2>&1 & echo $!
$ ps aux | grep sleep
ogi              4324   0.0  0.0  2432784    472 s001  R+    4:45PM   0:00.00 grep sleep
ogi              4309   0.0  0.0  2432764    468   ??  S     4:44PM   0:00.00 sleep 100000

file17.txt

$ rails runner "JobTask.cancel(4308)"
$

file18.txt

$ ps aux | grep test_command
ogi              4456   0.0  0.0  2424588    388 s001  R+    4:48PM   0:00.00 grep test_command
$ ps aux | grep sleep
ogi              4467   0.0  0.0  2432784    508 s001  R+    4:50PM   0:00.00 grep sleep

file19.txt

        system_command "kill -TERM -#{pgid}"
        p "canceled!"

file20.txt

$ rails runner JobTask.execute
"4520"
$ ps -p 4520 -o "pgid"
 PGID
 4449
$ ps 4449
  PID   TT  STAT      TIME COMMAND
 4449   ??  Ss     0:05.35 spring app    | background_linux_command | started 8 mins ago | development mode

file23.txt

$ rails runner JobTask.execute
"4877"
$ ps -p 4877 -o "pgid"
 PGID
 4875
$ ps 4875
  PID   TT  STAT      TIME COMMAND

file24.txt

$ rails c
Loading development environment (Rails 4.1.8)
irb(main):001:0> JobTask.execute
=> 5003
irb(main):002:0> "5005"

irb(main):003:0* exit
$ ps -p 5005 -o "pgid"
 PGID
 5003
$ ps 5003
  PID   TT  STAT      TIME COMMAND
 5003   ??  Z      0:00.00 (ruby)

file25.txt

$ rails runner "JobTask.cancel(4877)"
"canceled!"
$ ps aux | grep test_command
ogi              4951   0.0  0.0  2432784    488 s001  R+    5:18PM   0:00.00 grep test_command
$ ps aux | grep sleep
ogi              4958   0.0  0.0  2432784    500 s001  R+    5:18PM   0:00.00 grep sleep

file27.txt

$ rails runner JobTask.execute
"5507"
$ ps aux | grep test_command
ogi              5522   0.0  0.0  2432784    496 s001  R+    5:49PM   0:00.00 grep test_command
ogi              5507   0.0  0.0  2442580    568   ??  S     5:49PM   0:00.00 sh -c tmp/test_command > tmp/test.log 2>&1 & echo $!
$ ps aux | grep sleep
ogi              5529   0.0  0.0  2424588    404 s001  R+    5:49PM   0:00.00 grep sleep
ogi              5508   0.0  0.0  2432764    468   ??  S     5:49PM   0:00.00 sleep 100000

file28.txt

$ rails runner "JobTask.cancel(5507)"
"canceled!"
$ ps aux | grep test_command
ogi              5572   0.0  0.0  2442000    616 s001  S+    5:50PM   0:00.00 grep test_command
$ ps aux | grep sleep
ogi              5579   0.0  0.0  2432784    512 s001  R+    5:50PM   0:00.00 grep sleep

file29.txt

$ ls tmp/
cache       test.log    test_command
$ cat tmp/test_command
        echo "start sleep"
        sleep 100000
        echo "end sleep"
$ cat tmp/test.log
start sleep

file3.txt

$ rails runner JobTask.execute
3377

file4.txt

$ ps aux | grep test_command
ogi              3388   0.0  0.0  2432784    580 s001  R+    3:37PM   0:00.00 grep test_command
ogi              3378   0.0  0.0  2442580    580   ??  S     3:35PM   0:00.00 sh -c test_command > test.log 2>&1 &

file6.txt

$ rails runner JobTask.execute
"3836"

file7.txt

$ ps aux | grep test_command
ogi              3847   0.0  0.0  2432784    524 s001  R+    4:08PM   0:00.00 grep test_command
ogi              3836   0.0  0.0  2442580    580   ??  S     4:08PM   0:00.00 sh -c test_command > test.log 2>&1 &

file8.txt

$ rails runner "JobTask.cancel(3836)"

file9.txt

$ ps aux | grep test_command
ogi              3944   0.0  0.0  2423368    184 s001  R+    4:14PM   0:00.00 grep test_command

job_task.rb

class JobTask
  class << self
    def execute
      execute_job
    end

    def cancel(pid)
      command = "ps -p #{pid} -o \"pgid\""
      pgid = system_command(command).lines.to_a.last.lstrip.chomp
      if pgid =~ /[0-9]/
        system_command "kill -TERM -#{pgid}"
        p "canceled!"
      else
        Rails.logger.error 'Process was not found'
      end
    end
    private

    def create_command
      command = <<-"EOS"
        echo "start sleep"
        sleep 100000
        echo "end sleep"
      EOS
      script_path = "tmp/test_command"
      File.open(script_path, "w", 0755) do |f|
        f.write command
      end

      # execute background and return pid
      "#{script_path} > tmp/test.log 2>&1 & echo $!"
    end

    def execute_job
      begin
        fork do
          Process.setsid
          pid = system_command(create_command).lstrip.chomp
          if pid =~ /[0-9]/
            p pid
          else
            Rails.logger.error 'command has not pid'
          end
        end
      rescue => e
        Rails.logger.error e.message
      end
    end

    def system_command(command)
      `#{command}`
    end
  end
end

test_command

sleep 100000